User:NationalRegisterBot/AllNRHPPages/O

O

 * 1) O Street Market
 * 2) O'Bannon Homestead
 * 3) O'Bannon Mill
 * 4) O'Blenis House
 * 5) O'Brien County Courthouse
 * 6) O'Brien Electric Priming Company
 * 7) O'Brien General Store and Post Office
 * 8) O'Brien–Peuschel Farmstead
 * 9) O'Connor House (St. Thomas, North Dakota)
 * 10) O'Connor–Proctor Building
 * 11) O'Dea House (Berwyn Heights, Maryland)
 * 12) O'Donel House and Farm
 * 13) O'Donnell Building
 * 14) O'Donnell House (Sumter, South Carolina)
 * 15) O'Fallons Bluff
 * 16) O'Hanlon Building
 * 17) O'Hara Waltham Dial factory
 * 18) O'Kane Building
 * 19) O'Kane Market and O'Kane Building
 * 20) O'Kane-Jacobs House
 * 21) O'Kelly's Chapel
 * 22) O'Leno State Park
 * 23) O'Neill Site
 * 24) O'Reilly House
 * 25) O'Shaughnessy Dam (Ohio)
 * 26) O'Shea Building
 * 27) O. Arthur Kirkman House and Outbuildings
 * 28) O. B. McFadden House
 * 29) O. C. Barber Barn No. 1
 * 30) O. C. Barber Colt Barn
 * 31) O. C. Barber Creamery
 * 32) O. C. Barber Machine Barn
 * 33) O. C. Barber Piggery
 * 34) O. E. Payne House
 * 35) O. E. Rolvaag House
 * 36) O. E. Walker House
 * 37) O. F. Short House
 * 38) O. H. Booth Hose Company
 * 39) O. Henry Hall
 * 40) O. J. Daniels House
 * 41) O. K. Palmer House
 * 42) O. T. Bassett Tower
 * 43) O. W. Gardner House
 * 44) O.A.E. Blyberg House
 * 45) O.B. Grant House
 * 46) O.D. Gunn Trade and Sale Barn
 * 47) O.F. and Lulu E. Fryer House
 * 48) O.H.P. Tanner House
 * 49) O.J. Walker
 * 50) O.L. Dunaway House
 * 51) O.M. Edwards Building
 * 52) O.P. Wickham House
 * 53) OK Theatre
 * 54) OTO Homestead and Dude Ranch
 * 55) Oahu Railway and Land Company
 * 56) Oak Alley Plantation
 * 57) Oak Ballroom
 * 58) Oak Cemetery
 * 59) Oak Circle Historic District
 * 60) Oak City Christian Church
 * 61) Oak Creek Parkway
 * 62) Oak Crest
 * 63) Oak Dell
 * 64) Oak Flat (Arizona)
 * 65) Oak Forest (Mechanicsville, Virginia)
 * 66) Oak Glen (Portsmouth, Rhode Island)
 * 67) Oak Grove (Altavista, Virginia)
 * 68) Oak Grove (Church Hill, Mississippi)
 * 69) Oak Grove (Eastville, Virginia)
 * 70) Oak Grove (Erwin, North Carolina)
 * 71) Oak Grove (Hampton County, South Carolina)
 * 72) Oak Grove (La Plata, Maryland)
 * 73) Oak Grove (Manakin-Sabot, Virginia)
 * 74) Oak Grove Butterfield Stage Station
 * 75) Oak Grove Cemetery (Conway, Arkansas)
 * 76) Oak Grove Cemetery (Des Arc, Arkansas)
 * 77) Oak Grove Cemetery (Fall River, Massachusetts)
 * 78) Oak Grove Cemetery (Falmouth, Massachusetts)
 * 79) Oak Grove Cemetery (Gloucester, Massachusetts)
 * 80) Oak Grove Cemetery (New Bedford, Massachusetts)
 * 81) Oak Grove Community House
 * 82) Oak Grove Farm
 * 83) Oak Grove Methodist Church
 * 84) Oak Grove Missionary Baptist Church
 * 85) Oak Grove Rosenwald School
 * 86) Oak Grove School (Grant County, Arkansas)
 * 87) Oak Grove School (Prairieville, Alabama)
 * 88) Oak Grove School (Winston-Salem, North Carolina)
 * 89) Oak Hall (Brentwood, Tennessee)
 * 90) Oak Hall (Bunkie, Louisiana)
 * 91) Oak Hall Historic District
 * 92) Oak Hill (Annandale, Virginia)
 * 93) Oak Hill (Calvert City, Kentucky)
 * 94) Oak Hill (Chillicothe, Ohio)
 * 95) Oak Hill (Colonial Heights, Virginia)
 * 96) Oak Hill (Cumberland, Virginia)
 * 97) Oak Hill (Delaplane, Virginia)
 * 98) Oak Hill (James Monroe house)
 * 99) Oak Hill (Linlithgo, New York)
 * 100) Oak Hill Cemetery (Bartow, Florida)
 * 101) Oak Hill Cemetery (Birmingham, Alabama)
 * 102) Oak Hill Cemetery (Cedar Rapids, Iowa)
 * 103) Oak Hill Cemetery (Evansville, Indiana)
 * 104) Oak Hill Cemetery (Lawrence, Kansas)
 * 105) Oak Hill Cemetery (Lebanon, Indiana)
 * 106) Oak Hill Cemetery (Lewistown, Illinois)
 * 107) Oak Hill Cemetery (Newnan, Georgia)
 * 108) Oak Hill Cemetery (Oak Hill, New York)
 * 109) Oak Hill Cemetery (Pontiac, Michigan)
 * 110) Oak Hill Cemetery Chapel (Bellows Falls, Vermont)
 * 111) Oak Hill Cemetery Chapel (Washington, D.C.)
 * 112) Oak Hill Cottage
 * 113) Oak Hill Country Club
 * 114) Oak Hill Estate
 * 115) Oak Hill Farm
 * 116) Oak Hill Historic District (Fort Dodge, Iowa)
 * 117) Oak Hill Historic District (Hagerstown, Maryland)
 * 118) Oak Hill Historic District (Oak Hill, Alabama)
 * 119) Oak Hill Mausoleum
 * 120) Oak Hill Methodist Episcopal Church
 * 121) Oak Hill Park Historic District
 * 122) Oak Hill School House
 * 123) Oak Hill Welsh Congregational Church
 * 124) Oak Hill station
 * 125) Oak Hills, Oregon
 * 126) Oak Island (South Carolina)
 * 127) Oak Island Life Saving Station
 * 128) Oak Island Light
 * 129) Oak Knoll (Winchester, Massachusetts)
 * 130) Oak Lane Historic District
 * 131) Oak Lawn (Charlottesville, Virginia)
 * 132) Oak Lawn (Huntsboro, North Carolina)
 * 133) Oak Lawn (Madison Heights, Virginia)
 * 134) Oak Lawn (Ridgely, Maryland)
 * 135) Oak Lawn Farm Dairy Barn
 * 136) Oak Lawn Methodist Episcopal Church, South
 * 137) Oak Lodge
 * 138) Oak Park Conservatory
 * 139) Oak Park Historic District
 * 140) Oak Park Village Hall
 * 141) Oak Place (Huntsville, Alabama)
 * 142) Oak Plain Presbyterian Church
 * 143) Oak Ridge (Danville, Virginia)
 * 144) Oak Ridge Apartments
 * 145) Oak Ridge Cemetery
 * 146) Oak Ridge Historic District
 * 147) Oak Ridge Military Academy
 * 148) Oak Ridge Railroad Overpass
 * 149) Oak Ridge gatehouses
 * 150) Oak Spring Farm
 * 151) Oak Square School
 * 152) Oak Street Garage
 * 153) Oak Street School (Fulton, New York)
 * 154) Oak Top
 * 155) Oakcliff
 * 156) Oakdale (Floyd, Virginia)
 * 157) Oakdale (Pennsbury Township, Pennsylvania)
 * 158) Oakdale Cemetery (Hendersonville, North Carolina)
 * 159) Oakdale Cotton Mill Village
 * 160) Oakdale Historic District
 * 161) Oakdale Manor
 * 162) Oakdale Memorial Gardens
 * 163) Oakdale Public School
 * 164) Oakdale School (Madison, Indiana)
 * 165) Oakdale Village Historic District
 * 166) Oakdene (Staunton, Virginia)
 * 167) Oakenshawe Historic District
 * 168) Oakes Estate
 * 169) Oakes National Bank Block
 * 170) Oakes Post Office
 * 171) Oakes-Wood House
 * 172) Oakey Streak Methodist Episcopal Church
 * 173) Oakfield station
 * 174) Oakforest
 * 175) Oakham Center Historic District
 * 176) Oakham Farm
 * 177) Oakhill (Marshall, Michigan)
 * 178) Oakhurst (Emelle, Alabama)
 * 179) Oakhurst Historic District
 * 180) Oakhurst Links
 * 181) Oakhurst–Gildersleeve Neighborhood Historic District
 * 182) Oaklana
 * 183) Oakland (9 Oakhurst Drive, Natchez, Mississippi)
 * 184) Oakland (Airlie, North Carolina)
 * 185) Oakland (Bryantown, Maryland)
 * 186) Oakland (El Dorado, Arkansas)
 * 187) Oakland (Gallatin, Tennessee)
 * 188) Oakland (Montpelier, Virginia)
 * 189) Oakland (Parkersburg, West Virginia)
 * 190) Oakland Avenue Historic District
 * 191) Oakland Cemetery (Atlanta)
 * 192) Oakland Cemetery (Camden, Arkansas)
 * 193) Oakland Cemetery (Fort Dodge, Iowa)
 * 194) Oakland Cemetery (Princeton, Illinois)
 * 195) Oakland Cemetery (Trenton, Tennessee)
 * 196) Oakland City Hall
 * 197) Oakland Farm
 * 198) Oakland Grove Presbyterian Church
 * 199) Oakland Hall
 * 200) Oakland Historic District (Oakland, Maryland)
 * 201) Oakland Historic District (Oakland, Oregon)
 * 202) Oakland Hotel
 * 203) Oakland Memorial Chapel
 * 204) Oakland Mill
 * 205) Oakland Mills Blacksmith House and Shop
 * 206) Oakland Mills Bridge
 * 207) Oakland Park Elementary School
 * 208) Oakland Plantation (Beech Island, South Carolina)
 * 209) Oakland Plantation (Carvers, North Carolina)
 * 210) Oakland Plantation (Fort Motte, South Carolina)
 * 211) Oakland Plantation (Natchitoches Parish, Louisiana)
 * 212) Oakland Plantation (Tarboro, North Carolina)
 * 213) Oakland Plantation House (Gurley, Louisiana)
 * 214) Oakland Plantation House (Mount Pleasant, South Carolina)
 * 215) Oakland Presbyterian Church
 * 216) Oakland Public Library (Oakland, Maine)
 * 217) Oakland Public School
 * 218) Oakland station (Maryland)
 * 219) Oakland, Rhode Island
 * 220) Oakland-Fraternal Cemetery
 * 221) Oaklandon Historic District
 * 222) Oaklands (Gardiner, Maine)
 * 223) Oaklands (West Whiteland Township, Pennsylvania)
 * 224) Oaklands Historic House Museum
 * 225) Oakland–Dousman Historic District
 * 226) Oaklawn (Huntsville, Alabama)
 * 227) Oaklawn Cemetery
 * 228) Oaklawn Farm
 * 229) Oaklawn Garden
 * 230) Oaklawn Manor
 * 231) Oaklawn Plantation (Natchez, Louisiana)
 * 232) Oaklawn, Rhode Island
 * 233) Oakleigh Garden Historic District
 * 234) Oakleigh Historic Complex (Mobile, Alabama)
 * 235) Oaklette Historic District
 * 236) Oakley (Gallatin, Tennessee)
 * 237) Oakley (Heathsville, Virginia)
 * 238) Oakley (Spotsylvania County, Virginia)
 * 239) Oakley (Upperville, Virginia)
 * 240) Oakley Chapel African Methodist Episcopal Church
 * 241) Oakley Farm (Warm Springs, Virginia)
 * 242) Oakley High School Stadium
 * 243) Oakley Hill
 * 244) Oakley, Idaho
 * 245) Oaklyn Plantation
 * 246) Oakmont (Greenville, North Carolina)
 * 247) Oakmont Country Club
 * 248) Oakridge (Blackstone, Virginia)
 * 249) Oaks Cloister
 * 250) Oaks Hotel
 * 251) Oaks II
 * 252) Oakslea Place
 * 253) Oakton Gables
 * 254) Oakton Historic District
 * 255) Oakton Trolley Station
 * 256) Oakwood (Fauquier County, Virginia)
 * 257) Oakwood (Fayette, Missouri)
 * 258) Oakwood (Gadsden, South Carolina)
 * 259) Oakwood (Harwood, Maryland)
 * 260) Oakwood Avenue Presbyterian Church
 * 261) Oakwood Cemetery (Austin, Texas)
 * 262) Oakwood Cemetery (Fort Worth, Texas)
 * 263) Oakwood Cemetery (Niagara Falls, New York)
 * 264) Oakwood Cemetery (Troy, New York)
 * 265) Oakwood Cemetery Chapel (Allegan, Michigan)
 * 266) Oakwood Cemetery Chapel (Cuyahoga Falls, Ohio)
 * 267) Oakwood Cemetery Mausoleum
 * 268) Oakwood Estate
 * 269) Oakwood Historic District (Hickory, North Carolina)
 * 270) Oakwood Historic District (High Point, North Carolina)
 * 271) Oakwood–Chimborazo Historic District
 * 272) Oaky Grove
 * 273) Oark School-Methodist Church
 * 274) Oasis Court
 * 275) Oates Building
 * 276) Oates House
 * 277) Oates–Reynolds Memorial Building
 * 278) Oatlands Historic House & Gardens
 * 279) Oatman Drug Company Building
 * 280) Oatman Filling Station
 * 281) Oats Park Grammar School
 * 282) Obadiah Smith House
 * 283) Obediah Barber Homestead
 * 284) Obediah Farrar House
 * 285) Obediah Shirley House
 * 286) Obediah Winston Farm
 * 287) Oberg-Metcalf House
 * 288) Oberlin College
 * 289) Oberlin station
 * 290) Obidiah Dingee House
 * 291) Obion County Courthouse
 * 292) Obion Mounds
 * 293) Obligation (Harwood, Maryland)
 * 294) Oblong Friends Meeting House
 * 295) Observatory Hill Mound Group
 * 296) Observatory Historic District
 * 297) Observer Building
 * 298) Obsidian Cliff
 * 299) Obsidian Cliff Kiosk
 * 300) Ocala Historic Commercial District
 * 301) Ocala Historic District
 * 302) Ocala Union Station
 * 303) Occidental Life Building
 * 304) Occidental Life Insurance Company Building
 * 305) Occoneechee Speedway
 * 306) Occoquan Historic District
 * 307) Occum Hydroelectric Plant and Dam
 * 308) Ocean City 34th Street Station
 * 309) Ocean City City Hall
 * 310) Ocean City Life-Saving Station (New Jersey)
 * 311) Ocean City Residential Historic District
 * 312) Ocean City Tenth Street Station
 * 313) Ocean County Courthouse
 * 314) Ocean Drive Historic District
 * 315) Ocean Forest Country Club
 * 316) Ocean Grove, New Jersey
 * 317) Ocean Hall
 * 318) Ocean Park Historic Buildings
 * 319) Ocean Parkway (Brooklyn)
 * 320) Ocean Parkway Jewish Center
 * 321) Ocean Parkway station
 * 322) Ocean Road Historic District
 * 323) Ocean Spray Hotel
 * 324) Ocean Wave (shipwreck)
 * 325) Ocean to Ocean Bridge
 * 326) Oceana Neighborhood Historic District
 * 327) Oceanside City Hall and Fire Station
 * 328) Ochee Spring Quarry
 * 329) Ochlocknee Missionary Baptist Church and Cemetery
 * 330) Ochre Point–Cliffs Historic District
 * 331) Ocilla Public School
 * 332) Ocmulgee Mounds National Historical Park
 * 333) Ocoee Christian Church (Ocoee, Florida)
 * 334) Ocoee Dam No. 1
 * 335) Ocoee Dam No. 2
 * 336) Ocoee Dam No. 3
 * 337) Ocoee Street Historic District
 * 338) Oconaluftee (Great Smoky Mountains)
 * 339) Oconaluftee Baptist Church
 * 340) Oconee County Cage
 * 341) Oconee County Courthouse (1956)
 * 342) Oconee Hill Cemetery
 * 343) Oconee State Park
 * 344) Oconee Station State Historic Site
 * 345) Oconee Street School
 * 346) Oconomowoc station
 * 347) Oconto County Courthouse
 * 348) Ocqueoc Falls Highway–Ocqueoc River Bridge
 * 349) Ocqueoc Outdoor Center
 * 350) Ocracoke Historic District
 * 351) Ocracoke Light
 * 352) Octagon Barn, Otter Township
 * 353) Octagon Barn, Richland Township
 * 354) Octagon Building (Santa Cruz, California)
 * 355) Octagon Cottage (Rocky Hill, Kentucky)
 * 356) Octagon Hall
 * 357) Octagon House (Barrington, Illinois)
 * 358) Octagon House (Columbus, Georgia)
 * 359) Octagon House (Danbury, Connecticut)
 * 360) Octagon House (Fond du Lac, Wisconsin)
 * 361) Octagon House (Laurens, South Carolina)
 * 362) Octagon House (Reading, Massachusetts)
 * 363) Octagon House (Stamford, Connecticut)
 * 364) Octagon House (Watertown, Wisconsin)
 * 365) Octagon House (Westfield, Massachusetts)
 * 366) Octagon Round Barn, Indian Creek Township
 * 367) Octagon Stone Schoolhouse
 * 368) Octagonal Poultry House
 * 369) Octagonal Schoolhouse (Cowgill's Corner, Delaware)
 * 370) Octagonal Schoolhouse (Essex, New York)
 * 371) Octonia Stone
 * 372) Octorara Farm
 * 373) Odalmelech
 * 374) Odd Fellows Block (Afton, Iowa)
 * 375) Odd Fellows Block (Grand Forks, North Dakota)
 * 376) Odd Fellows Block (Lewiston, Maine)
 * 377) Odd Fellows Building (Casper, Wyoming)
 * 378) Odd Fellows Building (Gary, South Dakota)
 * 379) Odd Fellows Building (Malden, Massachusetts)
 * 380) Odd Fellows Building (Owensboro, Kentucky)
 * 381) Odd Fellows Building (Pikeville, Kentucky)
 * 382) Odd Fellows Building (Portland, Oregon)
 * 383) Odd Fellows Building (Raleigh, North Carolina)
 * 384) Odd Fellows Building (Red Bluff, California)
 * 385) Odd Fellows Building and Auditorium
 * 386) Odd Fellows Cemetery (Starkville, Mississippi)
 * 387) Odd Fellows Hall (Alexandria, Virginia)
 * 388) Odd Fellows Hall (Baltimore, 1891)
 * 389) Odd Fellows Hall (Beaver, Utah)
 * 390) Odd Fellows Hall (Big Horn, Wyoming)
 * 391) Odd Fellows Hall (Blacksburg, Virginia)
 * 392) Odd Fellows Hall (Cambridge, Massachusetts)
 * 393) Odd Fellows Hall (Covington, Kentucky)
 * 394) Odd Fellows Hall (Eureka, California)
 * 395) Odd Fellows Hall (Gonzales, California)
 * 396) Odd Fellows Hall (Hilliard, Ohio)
 * 397) Odd Fellows Hall (La Grange, California)
 * 398) Odd Fellows Hall (Monticello, Iowa)
 * 399) Odd Fellows Hall (New York City)
 * 400) Odd Fellows Hall (Portsmouth, Ohio)
 * 401) Odd Fellows Hall (Salmon, Idaho)
 * 402) Odd Fellows Hall (Sandusky, Ohio)
 * 403) Odd Fellows Hall (Santa Ana, California)
 * 404) Odd Fellows Hall (Troy Mills, Iowa)
 * 405) Odd Fellows Home District
 * 406) Odd Fellows Home of Dell Rapids
 * 407) Odd Fellows Lodge (Bel Air, Maryland)
 * 408) Odd Fellows Lodge (Goldsboro, North Carolina)
 * 409) Odd Fellows Lodge and Temple
 * 410) Odd Fellows Opera Block
 * 411) Odd Fellows Rest Cemetery
 * 412) Odd Fellows Temple (East Liverpool, Ohio)
 * 413) Odd Fellows Temple (Lexington, Kentucky)
 * 414) Odd Fellows Temple (Pasadena, California)
 * 415) Odd Fellows Valley Lodge No. 189 Building
 * 416) Odd Fellows and Confederate Cemetery
 * 417) Odd Fellows' Cemetery Mound
 * 418) Odd Fellows' Hall (Beverly, Massachusetts)
 * 419) Odd Fellows' Hall (Buckland, Massachusetts)
 * 420) Odd Fellows' Home (Worcester, Massachusetts)
 * 421) Odd Fellows' Home for Orphans, Indigent and Aged
 * 422) Odd Fellows-Rebekah Hall (Cornish, Maine)
 * 423) Oddfellows Building
 * 424) Oddfellows Hall (Auburn, California)
 * 425) Oddfellows Hall (Fairbanks, Alaska)
 * 426) Oddfellows' Hall (East Providence, Rhode Island)
 * 427) Odell Building
 * 428) Odell House
 * 429) Odell-Locke-Randolph Cotton Mill
 * 430) Odeon Theater (Tucumcari, New Mexico)
 * 431) Odessa Historic District
 * 432) Odessa Ice Cream Company Building
 * 433) Oeldorf Building
 * 434) Oella, Maryland
 * 435) Oesterlein Machine Company-Fashion Frocks, Inc. Complex
 * 436) Off-the-Neck Historic District
 * 437) Offerman Building
 * 438) Office Bridge
 * 439) Office Hall
 * 440) Officers Quarters, Washington Navy Yard
 * 441) Officers Row
 * 442) Officers' Row Historic District
 * 443) Offshore Reefs Archeological District
 * 444) Offutt Covered Bridge
 * 445) Oficina de Telégrafo y Teléfono
 * 446) Ogden Apartment Hotel
 * 447) Ogden High School
 * 448) Ogden House (Swarthmore, Pennsylvania)
 * 449) Ogden Theatre
 * 450) Ogden-Fettie Site
 * 451) Ogden/Weber Municipal Building
 * 452) Ogdensburg Armory
 * 453) Ogdensburg Harbor Light
 * 454) Ogilvie Building
 * 455) Ogilvie Moses Farmhouse
 * 456) Ogilvie Watertower
 * 457) Ogle County Courthouse
 * 458) Oglebay Hall
 * 459) Oglebay Park
 * 460) Oglesby-Conrad House
 * 461) Oglethorpe University
 * 462) Ogontz Hall
 * 463) Ogunquit Memorial Library
 * 464) Ogunquit Playhouse
 * 465) Ogunquit, Maine
 * 466) Ohave Shalom Synagogue (Woodridge, New York)
 * 467) Oheka Castle
 * 468) Ohev Sholem Synagogue (New London, Connecticut)
 * 469) Ohev Sholom Temple
 * 470) Oheyawahi-Pilot Knob
 * 471) Ohio Baptist General Association Headquarters
 * 472) Ohio Boulevard–Deming Park Historic District
 * 473) Ohio City, Cleveland
 * 474) Ohio Company Land Office
 * 475) Ohio Farm Bureau Federation Offices
 * 476) Ohio Finance Building
 * 477) Ohio Governor's Mansion
 * 478) Ohio History Center
 * 479) Ohio Judicial Center
 * 480) Ohio Military Institute
 * 481) Ohio Moline Plow Building
 * 482) Ohio National Bank
 * 483) Ohio National Guard Armory
 * 484) Ohio Oil Company Building
 * 485) Ohio Stadium
 * 486) Ohio State Normal College at Kent
 * 487) Ohio State Reformatory
 * 488) Ohio Statehouse
 * 489) Ohio Street Bridge
 * 490) Ohio Street Methodist Episcopal Church Complex
 * 491) Ohio Theatre (Columbus, Ohio)
 * 492) Ohio Theatre (Lima, Ohio)
 * 493) Ohio Theatre (Loudonville, Ohio)
 * 494) Ohio Theatre (Toledo, Ohio)
 * 495) Ohio University Lancaster historic bridges
 * 496) Ohio and Erie Canal
 * 497) Ohkay Owingeh, New Mexico
 * 498) Ohlman-Shannon House
 * 499) Ohringer Building
 * 500) Oil Capital Historic District (Tulsa, Oklahoma)
 * 501) Oil City Armory
 * 502) Oil City Downtown Commercial Historic District
 * 503) Oil City North Side Historic District
 * 504) Oil City South Side Historic District
 * 505) Oil Springs Methodist Church
 * 506) Oil and Gas Building
 * 507) Ojibway Fire Tower
 * 508) Ojo Caliente Hot Springs
 * 509) Ojo Caliente Hot Springs Round Barn
 * 510) Okahumpka Rosenwald School
 * 511) Okeechobee Battlefield
 * 512) Okehocking Historic District
 * 513) Oklahoma A & M College Agronomy Barn and Seed House
 * 514) Oklahoma City Discovery Well
 * 515) Oklahoma City Ford Motor Company Assembly Plant
 * 516) Oklahoma City National Memorial
 * 517) Oklahoma City University
 * 518) Oklahoma County Courthouse
 * 519) Oklahoma Judicial Center
 * 520) Oklahoma Natural Gas Company Building
 * 521) Oklahoma Odd Fellows Home at Checotah
 * 522) Oklahoma Presbyterian College
 * 523) Oklahoma Publishing Company Building
 * 524) Oklahoma State Capitol
 * 525) Okmulgee Downtown Historic District
 * 526) Okmulgee Public Library
 * 527) Okoboji Bridge
 * 528) Okolona (Middletown, Delaware)
 * 529) Okolona College
 * 530) Okolona Colored High School Gymnasium
 * 531) Ola Babcock Miller Building
 * 532) Olaf Lee House
 * 533) Olaf Stordahl Barn
 * 534) Olallie Lake Guard Station
 * 535) Olana State Historic Site
 * 536) Olcovich–Meyers House
 * 537) Old Administration Building (Bryce Canyon National Park)
 * 538) Old Administrative Area Historic District
 * 539) Old Adobe Barn
 * 540) Old Albany Academy Building
 * 541) Old Albany Post Road
 * 542) Old Albany Schoolhouse
 * 543) Old Albuquerque Municipal Airport Building
 * 544) Old Alexander House
 * 545) Old Allamakee County Courthouse (Lansing, Iowa)
 * 546) Old Allamakee County Courthouse (Waukon, Iowa)
 * 547) Old Allegany County Courthouse
 * 548) Old Allegheny Rows Historic District
 * 549) Old Alpha Tau Omega Fraternity House (Eugene, Oregon)
 * 550) Old Alton Bridge
 * 551) Old Anchorage City Hall
 * 552) Old Appleton Bridge
 * 553) Old Arkansas City High School
 * 554) Old Armijo School
 * 555) Old Armory (Williston, North Dakota)
 * 556) Old Asbury Methodist Church
 * 557) Old Ashland Post Office
 * 558) Old Ashton Historic District
 * 559) Old Athens, Alabama Main Post Office
 * 560) Old Athol High School
 * 561) Old Attleboro Post Office
 * 562) Old Augusta Historic Site
 * 563) Old Bacon Academy
 * 564) Old Baker County Courthouse
 * 565) Old Baldy (Lynch, Nebraska)
 * 566) Old Baltimore College of Dental Surgery
 * 567) Old Bank of America Building (Red Bluff, California)
 * 568) Old Bank of Amity
 * 569) Old Bank of Louisville
 * 570) Old Banks County Courthouse
 * 571) Old Baptist Parsonage (Scotch Plains, New Jersey)
 * 572) Old Barn (Canton, Massachusetts)
 * 573) Old Barnhill Building
 * 574) Old Barracks Museum
 * 575) Old Bartow County Courthouse
 * 576) Old Batesburg Grade School
 * 577) Old Batesburg-Leesville High School
 * 578) Old Battle Creek Post Office
 * 579) Old Bayfield County Courthouse
 * 580) Old Bayview Cemetery
 * 581) Old Bedford County Jail
 * 582) Old Beechwold Historic District
 * 583) Old Bell Telephone Building (Osceola, Arkansas)
 * 584) Old Belleair Town Hall
 * 585) Old Belvidere High School (Belvidere, Illinois)
 * 586) Old Bend High School
 * 587) Old Bennington High School
 * 588) Old Bennington Post Office
 * 589) Old Bennington, Vermont
 * 590) Old Benton-Sardis Road Bridge
 * 591) Old Bergen Church
 * 592) Old Berkeley City Hall
 * 593) Old Berkeley County Courthouse (South Carolina)
 * 594) Old Berlin High School
 * 595) Old Berrien County Courthouse Complex
 * 596) Old Berrien County Jail
 * 597) Old Beta Theta Pi Fraternity House
 * 598) Old Beth Israel Synagogue (Greenville, South Carolina)
 * 599) Old Bethany Church
 * 600) Old Bethel Methodist Church (Arkansas)
 * 601) Old Bethel United Methodist Church
 * 602) Old Billerica Road Historic District
 * 603) Old Bittermann Building
 * 604) Old Blenheim Bridge
 * 605) Old Bloomfield
 * 606) Old Bloomington High School
 * 607) Old Bluff Presbyterian Church
 * 608) Old Bnai Zion Synagogue
 * 609) Old Boardman Bridge
 * 610) Old Borges Ranch
 * 611) Old Bourne High School building
 * 612) Old Bradford County Courthouse
 * 613) Old Brewer High School
 * 614) Old Brick Church (Athens, Vermont)
 * 615) Old Brick Church (Bacon's Castle, Virginia)
 * 616) Old Brick Church (Fairfield County, South Carolina)
 * 617) Old Brick Church (Iowa City, Iowa)
 * 618) Old Brick House
 * 619) Old Brick House (Biloxi, Mississippi)
 * 620) Old Brick Post Office (Wickenburg, Arizona)
 * 621) Old Brick Presbyterian Church
 * 622) Old Brick Store
 * 623) Old Bridge (unincorporated community), New Jersey
 * 624) Old Bridgeville Fire House
 * 625) Old Bristol High School
 * 626) Old Broad Street Presbyterian Church and Cemetery
 * 627) Old Broadway Synagogue
 * 628) Old Brooklyn Fire Headquarters
 * 629) Old Brown's Mill School
 * 630) Old Brulay Plantation
 * 631) Old Brunswick County Courthouse (North Carolina)
 * 632) Old Bunnell State Bank Building
 * 633) Old Burying Ground (Beaufort, North Carolina)
 * 634) Old Burying Ground (Littleton, Massachusetts)
 * 635) Old Burying Ground (Stoneham, Massachusetts)
 * 636) Old Burying Ground (Watertown, Massachusetts)
 * 637) Old Cadillac City Hall
 * 638) Old Cahokia Courthouse
 * 639) Old Calaboose
 * 640) Old Calhoun County Courthouse
 * 641) Old California City Hall and Fire Station
 * 642) Old Cambridge Baptist Church
 * 643) Old Cambridge Historic District
 * 644) Old Cambridgeport Historic District
 * 645) Old Camden Post Office
 * 646) Old Camp Verde
 * 647) Old Campus District, University of South Carolina
 * 648) Old Campus Historic District (St. Lawrence University)
 * 649) Old Cann Mansion House
 * 650) Old Cape May County Courthouse Building
 * 651) Old Capitol Building
 * 652) Old Castle (Rockport, Massachusetts)
 * 653) Old Castle Hall
 * 654) Old Catonsville High School
 * 655) Old Catonsville Historic District
 * 656) Old Cawker City Library
 * 657) Old Cedar Baptist Church
 * 658) Old Center Burying Yard
 * 659) Old Central
 * 660) Old Central Fire Station (North Little Rock, Arkansas)
 * 661) Old Central Fire Station (Pittsfield, Massachusetts)
 * 662) Old Central Grammar School
 * 663) Old Central High School (Kalamazoo, Michigan)
 * 664) Old Central High School (Pittsfield, Massachusetts)
 * 665) Old Centre Historic District
 * 666) Old Challis Historic District
 * 667) Old Chapel (Amherst, Massachusetts)
 * 668) Old Chapel (Millwood, Virginia)
 * 669) Old Chapel Church
 * 670) Old Chapel Hall
 * 671) Old Chapel Hill Cemetery
 * 672) Old Chappaqua Historic District
 * 673) Old Charles Town Historic District
 * 674) Old Chattahoochee County Courthouse
 * 675) Old Cheboygan County Courthouse
 * 676) Old Chelmsford Garrison House
 * 677) Old Chestnut Hill Historic District
 * 678) Old Chicago Main Post Office
 * 679) Old Chief Joseph Gravesite
 * 680) Old China Trail
 * 681) Old Chiswell Place
 * 682) Old Christ Church (Bethel, Vermont)
 * 683) Old Christ Church (Laurel, Delaware)
 * 684) Old Christ Church (Pensacola, Florida)
 * 685) Old Christiansburg Industrial Institute
 * 686) Old Churchyard Cemetery
 * 687) Old Citrus County Courthouse
 * 688) Old City Cemetery (Columbus, Georgia)
 * 689) Old City Cemetery (Lynchburg, Virginia)
 * 690) Old City Hall (Boston)
 * 691) Old City Hall (Davenport, Iowa)
 * 692) Old City Hall (Fairbanks, Alaska)
 * 693) Old City Hall (Gilroy, California)
 * 694) Old City Hall (Knoxville)
 * 695) Old City Hall (Lancaster, Pennsylvania)
 * 696) Old City Hall (Mobile, Alabama)
 * 697) Old City Hall (Richmond, Virginia)
 * 698) Old City Hall (St. Charles, Missouri)
 * 699) Old City Hall (Tacoma, Washington)
 * 700) Old City Hall (Williamsport, Pennsylvania)
 * 701) Old City Hall Historic District
 * 702) Old City Hall and Engine House
 * 703) Old City Road Stone Arch Bridge
 * 704) Old City Waterworks
 * 705) Old City, Philadelphia
 * 706) Old Clarke County Courthouse (Virginia)
 * 707) Old Clarksville site
 * 708) Old Classroom Building, Union College
 * 709) Old Clay County Courthouse (West Virginia)
 * 710) Old Clifty Church
 * 711) Old Clinch County Jail
 * 712) Old Clinton Historic District
 * 713) Old Clock at Zion's First National Bank
 * 714) Old Clovis Post Office
 * 715) Old Cochecton Cemetery
 * 716) Old Cochrane Road Bridge
 * 717) Old College Hill Post Office
 * 718) Old College Historic District
 * 719) Old Colleton County Jail
 * 720) Old Collier County Courthouse
 * 721) Old Colony Cove Site
 * 722) Old Colony House
 * 723) Old Colony Iron Works-Nemasket Mills Complex
 * 724) Old Colorado City
 * 725) Old Conemaugh Borough Historic District
 * 726) Old Congregational Church (North Scituate, Rhode Island)
 * 727) Old Constitution House
 * 728) Old Cony High School
 * 729) Old Corinth Cemetery
 * 730) Old Corner Bookstore
 * 731) Old Cortez High School
 * 732) Old County Courthouse
 * 733) Old County Road South Historic District
 * 734) Old Courthouse (Buena Vista, Virginia)
 * 735) Old Courthouse Square (Lake Providence, Louisiana)
 * 736) Old Covered Bridge
 * 737) Old Crawfordsville High School
 * 738) Old Croton Dam
 * 739) Old Curtisville Historic District
 * 740) Old Custom House (Cairo, Illinois)
 * 741) Old Custom House (Monterey, California)
 * 742) Old Custom House (Yorktown, Virginia)
 * 743) Old Customs House (Knoxville, Tennessee)
 * 744) Old Customshouse (Erie, Pennsylvania)
 * 745) Old Customshouse (Wilmington, Delaware)
 * 746) Old Danish Church
 * 747) Old Dauphin Way Historic District
 * 748) Old Davidson County Courthouse (North Carolina)
 * 749) Old DeLand Memorial Hospital
 * 750) Old Deerfield Center Historic District
 * 751) Old Deerfield School
 * 752) Old Deery Inn
 * 753) Old Delta Democrat Times Building
 * 754) Old Denton
 * 755) Old Depot Museum
 * 756) Old Dillard High School
 * 757) Old District 10 Schoolhouse
 * 758) Old Donation Episcopal Church
 * 759) Old Douglas Center Historic District
 * 760) Old Dowlin Mill
 * 761) Old Downtown Des Moines Library
 * 762) Old Downtown Harrisburg Commercial Historic District
 * 763) Old Drawyers Church
 * 764) Old Dry Road
 * 765) Old DuPage County Courthouse
 * 766) Old Durand High School
 * 767) Old Dutch Church (Kingston, New York)
 * 768) Old Dutch Church Parsonage
 * 769) Old Dutch Church of Sleepy Hollow
 * 770) Old Dutch Parsonage
 * 771) Old Eagle Tavern
 * 772) Old East
 * 773) Old East Baltimore Historic District
 * 774) Old East Boston High School
 * 775) Old East Haven High School
 * 776) Old East Historic District
 * 777) Old East Paint Creek Lutheran Church
 * 778) Old Ebenezer Church
 * 779) Old Economy Village
 * 780) Old Eddyville Historic District
 * 781) Old Effingham County Courthouse
 * 782) Old Elm Spring Colony, South Dakota
 * 783) Old Engine Company 26 (Washington, D.C.)
 * 784) Old Engine Company No. 6
 * 785) Old Enon Road Stone Arch Culvert
 * 786) Old Episcopal Manse
 * 787) Old Essex County Jail
 * 788) Old Executive Mansion
 * 789) Old Faithful Historic District
 * 790) Old Faithful Inn
 * 791) Old Farm
 * 792) Old Farm Schoolhouse
 * 793) Old Fauquier County Jail
 * 794) Old Federal Building (Anchorage)
 * 795) Old Federal Building (Fairbanks, Alaska)
 * 796) Old Federal Building (Sault Ste. Marie)
 * 797) Old Federal Reserve Bank Building (Philadelphia)
 * 798) Old Federal Reserve Bank Building (San Francisco)
 * 799) Old Fellwock Auto Company
 * 800) Old Fernald-Laughton Memorial Hospital
 * 801) Old Finnish Lutheran Church
 * 802) Old Fire Engine House
 * 803) Old Fire House
 * 804) Old Fire House No. 4 (Kalamazoo, Michigan)
 * 805) Old Fire Station (Chester, Illinois)
 * 806) Old First Church (Huntington, New York)
 * 807) Old First Methodist Episcopal Church South
 * 808) Old First National Bank of Prineville
 * 809) Old First National Bank of Punta Gorda
 * 810) Old First Presbyterian Church (Kosciusko, Mississippi)
 * 811) Old First Presbyterian Church (Newark, Delaware)
 * 812) Old First Presbyterian Church (Newark, New Jersey)
 * 813) Old First Presbyterian Church (Wilmington, Delaware)
 * 814) Old First Reformed Church (Brooklyn)
 * 815) Old Florence Water Tower
 * 816) Old Ford Dairy
 * 817) Old Forge Farm
 * 818) Old Forge Farm (Middletown, Virginia)
 * 819) Old Fort (Miami, Missouri)
 * 820) Old Fort Bliss
 * 821) Old Fort Braden School
 * 822) Old Fort Church
 * 823) Old Fort Commercial Historic District
 * 824) Old Fort Harrod State Park
 * 825) Old Fort House (Columbus, Mississippi)
 * 826) Old Fort House (Fort Edward, New York)
 * 827) Old Fort Johnson
 * 828) Old Fort Madison High School
 * 829) Old Fort Park Archeological Site
 * 830) Old Fort Park and Golf Course
 * 831) Old Fort Pierce City Hall
 * 832) Old Fort Pierce Park
 * 833) Old Fort Pierce Post Office
 * 834) Old Fourth Ward Historic District
 * 835) Old Fourth Ward Southeast Historic District
 * 836) Old Frankfort Stone High School
 * 837) Old Franklin United Brethren Church
 * 838) Old Fremont Post Office
 * 839) Old Fresno Water Tower
 * 840) Old Friends Archeological Site
 * 841) Old Friendship United Methodist Church
 * 842) Old Frio County Jail
 * 843) Old Frostproof High School
 * 844) Old Gaissert Homeplace
 * 845) Old Garfield School (Salem, Oregon)
 * 846) Old Garrard County Jail
 * 847) Old Garrison House
 * 848) Old Georgetown City Hall
 * 849) Old Georgetown Road (Charleston County, South Carolina)
 * 850) Old Gerald School
 * 851) Old German Baptist Brethren Church (Winston-Salem)
 * 852) Old Germantown Academy and Headmasters' Houses
 * 853) Old Gillett Jail
 * 854) Old Glen Cove Post Office
 * 855) Old Gothic Barns
 * 856) Old Goucher College Buildings
 * 857) Old Government House (Augusta, Georgia)
 * 858) Old Governor's Mansion (Frankfort, Kentucky)
 * 859) Old Governor's Mansion (Milledgeville, Georgia)
 * 860) Old Grace Episcopal Church Rectory
 * 861) Old Grafton County Courthouse
 * 862) Old Grand Rapids Christian High School
 * 863) Old Grandin Library
 * 864) Old Gravesend Cemetery
 * 865) Old Gray Cemetery
 * 866) Old Gray County Courthouse
 * 867) Old Gray House
 * 868) Old Grayson County Courthouse and Clerk's Office
 * 869) Old Greencastle Historic District
 * 870) Old Greene County Courthouse
 * 871) Old Greenville (23WE637)
 * 872) Old Greenwich station
 * 873) Old Greenwood Cemetery
 * 874) Old Greenwood High School
 * 875) Old Grist Mill
 * 876) Old Guaranty Bank Building
 * 877) Old Gym (Vanderbilt University)
 * 878) Old Haines City National Guard Armory
 * 879) Old Hall County Courthouse (Georgia)
 * 880) Old Hamilton County Jail
 * 881) Old Hamilton Library
 * 882) Old Hampden Academy Building
 * 883) Old Hancock Central High School
 * 884) Old Hancock County Buildings
 * 885) Old Hanover High School
 * 886) Old Hansen Planetarium
 * 887) Old Harbor Historic District
 * 888) Old Harbor Reservation Parkways
 * 889) Old Harbor U.S. Life Saving Station
 * 890) Old Hardy County Courthouse
 * 891) Old Harrison County Courthouse (Iowa)
 * 892) Old Harrison County Courthouse (Texas)
 * 893) Old Hartwick Village Cemetery
 * 894) Old Hattiesburg High School
 * 895) Old Hawleyton Methodist Episcopal Church
 * 896) Old Headquarters Area Historic District
 * 897) Old Heidelberg Apartments
 * 898) Old Hemlock
 * 899) Old Hendry County Courthouse
 * 900) Old Hernando Elementary School
 * 901) Old Hickman Historic District
 * 902) Old Hickory United Methodist Church
 * 903) Old Higgins Farm Windmill
 * 904) Old High Middle School (Bentonville, Arkansas)
 * 905) Old Highway 16 Bridge
 * 906) Old Hill Place Bridge
 * 907) Old Holy Redeemer Catholic Church
 * 908) Old Homer Village Historic District
 * 909) Old Homestead (Aberdeen, Mississippi)
 * 910) Old Homestead (Enon Valley, Pennsylvania)
 * 911) Old Hoopes School
 * 912) Old Horry County Courthouse
 * 913) Old Hose House
 * 914) Old Hotel (Dumfries, Virginia)
 * 915) Old House (Cutchogue)
 * 916) Old House Plantation
 * 917) Old Huntington High School
 * 918) Old Huntington Jail
 * 919) Old Idaho State Penitentiary
 * 920) Old Indian Cemetery
 * 921) Old Indian Meeting House
 * 922) Old Indian River County Courthouse
 * 923) Old Indiana County Courthouse
 * 924) Old Indiana County Jail and Sheriff's Office
 * 925) Old Indianapolis City Hall
 * 926) Old Irion County Courthouse
 * 927) Old Iron County Courthouse
 * 928) Old Irontown, Utah
 * 929) Old Iroquois County Courthouse
 * 930) Old Isle of Wight Courthouse
 * 931) Old Jacoby Creek School
 * 932) Old Jail (Barnstable, Massachusetts)
 * 933) Old Jail (Gordo, Alabama)
 * 934) Old Jail (Muscatine, Iowa)
 * 935) Old Jail (Washington, Georgia)
 * 936) Old Jefferson Parish Courthouse
 * 937) Old Jeffersonville Historic District
 * 938) Old Joe (Norfork, Arkansas)
 * 939) Old Judy Church
 * 940) Old Kennebunk High School
 * 941) Old Kennett Meetinghouse
 * 942) Old Kentuck
 * 943) Old Kentucky Turnpike Historic District
 * 944) Old Killingly High School
 * 945) Old King's Highway Historic District
 * 946) Old Kingsport Presbyterian Church
 * 947) Old LSU Site
 * 948) Old La Grange Schoolhouse
 * 949) Old Ladore School
 * 950) Old Lafayette City Hall
 * 951) Old Lake County Courthouse (California)
 * 952) Old Lake County Courthouse (Florida)
 * 953) Old Lake Worth City Hall
 * 954) Old Lakeland High School
 * 955) Old Las Vegas Mormon Fort State Historic Park
 * 956) Old Laurel High School
 * 957) Old Lee County Courthouse
 * 958) Old Lehigh County Courthouse
 * 959) Old Lenox High School building
 * 960) Old Library (Bryn Mawr College)
 * 961) Old Library Building (Chattanooga, Tennessee)
 * 962) Old Library Building (Maysville, Kentucky)
 * 963) Old Linn County Jail
 * 964) Old Little Rock Central Fire Station
 * 965) Old Live Oak City Hall
 * 966) Old Livery Stable
 * 967) Old Livingston Parish Courthouse
 * 968) Old Lock Pump House, Chesapeake & Delaware Canal
 * 969) Old Log Church
 * 970) Old Logan County Courthouse (Kansas)
 * 971) Old Logan County Jail
 * 972) Old Lone Star Brewery
 * 973) Old Lordsburg High School
 * 974) Old Lorimier Cemetery
 * 975) Old Louisiana Governor's Mansion
 * 976) Old Louisiana State Capitol
 * 977) Old Louisville
 * 978) Old Lucerne Historic Residential District
 * 979) Old Lutheran Parsonage
 * 980) Old Lutz Elementary School
 * 981) Old Lyford High School
 * 982) Old Lyme Historic District
 * 983) Old Lynn High School
 * 984) Old M-94–Au Train River Bridge
 * 985) Old M-95–Michigamme River Bridge
 * 986) Old Mackinac Point Light
 * 987) Old Madison County Courthouse
 * 988) Old Maid's Orchard Mound
 * 989) Old Main (Arizona State University)
 * 990) Old Main (Augsburg University)
 * 991) Old Main (Bethany College)
 * 992) Old Main (California University of Pennsylvania)
 * 993) Old Main (Dakota College at Bottineau)
 * 994) Old Main (Eastern Illinois University)
 * 995) Old Main (Franklin College)
 * 996) Old Main (Iowa Wesleyan University)
 * 997) Old Main (Marshall University)
 * 998) Old Main (Minnesota State University, Mankato)
 * 999) Old Main (Nicholas County High School)
 * 1000) Old Main (North Park University)
 * 1001) Old Main (Texas State University)
 * 1002) Old Main (University of Arkansas)
 * 1003) Old Main (University of North Carolina at Pembroke)
 * 1004) Old Main (University of South Dakota)
 * 1005) Old Main (University of Wyoming)
 * 1006) Old Main (Utah State University)
 * 1007) Old Main (Wartburg College)
 * 1008) Old Main Street Historic District (Dubuque, Iowa)
 * 1009) Old Main Street Historic District (Racine, Wisconsin)
 * 1010) Old Main and Chemistry Building
 * 1011) Old Main at the Lutheran Home at Topton
 * 1012) Old Main, Augustana College
 * 1013) Old Main, Goethean Hall, and Diagnothian Hall
 * 1014) Old Main, Knox College
 * 1015) Old Main, Nebraska Wesleyan University
 * 1016) Old Main, Suomi College
 * 1017) Old Main, University of Arizona
 * 1018) Old Man House
 * 1019) Old Manatee County Courthouse
 * 1020) Old Mandan High School
 * 1021) Old Mansion
 * 1022) Old Marengo County Courthouse
 * 1023) Old Marion County Courthouse (Georgia)
 * 1024) Old Market (Louisville, Georgia)
 * 1025) Old Market (Omaha, Nebraska)
 * 1026) Old Market Building (Georgetown, South Carolina)
 * 1027) Old Market House (Galena, Illinois)
 * 1028) Old Martin County Courthouse
 * 1029) Old Masonic Hall (Bellville, Texas)
 * 1030) Old Masonic Hall (Benicia, California)
 * 1031) Old Masonic Hall (Louisville, Mississippi)
 * 1032) Old Masonic Temple (Marshall, Minnesota)
 * 1033) Old Mauch Chunk Historic District
 * 1034) Old McCulloch County Jail
 * 1035) Old McDonald County Courthouse
 * 1036) Old McHenry County Courthouse
 * 1037) Old McKenzie Fish Hatchery
 * 1038) Old McKinley High School
 * 1039) Old Medford High School
 * 1040) Old Medical College
 * 1041) Old Meigs County Courthouse
 * 1042) Old Merchants and Farmers Bank Building
 * 1043) Old Methodist District Parsonage
 * 1044) Old Michigan Avenue School
 * 1045) Old Michigan City Light
 * 1046) Old Middletown High School
 * 1047) Old Middletown Post Office
 * 1048) Old Midtown Historic District (Harrisburg)
 * 1049) Old Military Road
 * 1050) Old Mill (West Tisbury, Massachusetts)
 * 1051) Old Mill House
 * 1052) Old Mill Road Bridge
 * 1053) Old Mill Site Historic District
 * 1054) Old Mill State Park
 * 1055) Old Mill at Tinton Falls
 * 1056) Old Miller Hospital
 * 1057) Old Mine Park Archeological Site
 * 1058) Old Mine Road Historic District
 * 1059) Old Minnehaha County Courthouse
 * 1060) Old Mishawaka Carnegie Library
 * 1061) Old Mission Dam
 * 1062) Old Mission House
 * 1063) Old Mission Inn
 * 1064) Old Mission State Park
 * 1065) Old Mississippi State Capitol
 * 1066) Old Mobile Site
 * 1067) Old Monroe County Courthouse
 * 1068) Old Monroe School House
 * 1069) Old Morris County Courthouse
 * 1070) Old Morrison Mill
 * 1071) Old Mt. Carmel Cemetery, Wrought-Iron Cross Site
 * 1072) Old Muhlenberg County Jail
 * 1073) Old Mulkey Meetinghouse
 * 1074) Old Napa Register Building
 * 1075) Old Narragansett Cemetery
 * 1076) Old Narragansett Church
 * 1077) Old Nassau County Courthouse (New York)
 * 1078) Old Natchez Trace segments listed on the National Register of Historic Places
 * 1079) Old National Park Service Housing Historic District
 * 1080) Old National Pike Milestones
 * 1081) Old Naval Hospital
 * 1082) Old Naval Observatory
 * 1083) Old Nazareth Academy
 * 1084) Old Nebraska State Bank Building
 * 1085) Old Neck Historic District
 * 1086) Old Neighborhoods Historic District
 * 1087) Old New England Building
 * 1088) Old New York Evening Post Building
 * 1089) Old New-Gate Prison
 * 1090) Old Newark Comprehensive School
 * 1091) Old Newberry County Courthouse
 * 1092) Old Newburgh Presbyterian Church
 * 1093) Old Nicolet High School
 * 1094) Old Nogales City Hall and Fire Station
 * 1095) Old Norfolk City Hall
 * 1096) Old Norriton Presbyterian Church
 * 1097) Old North Carolina Mutual Life Insurance Company Building
 * 1098) Old North Cemetery (Concord, New Hampshire)
 * 1099) Old North Cemetery (Hartford, Connecticut)
 * 1100) Old North Cemetery (Portsmouth, New Hampshire)
 * 1101) Old North Cemetery (Truro, Massachusetts)
 * 1102) Old North Church
 * 1103) Old North End Historic District (Colorado Springs, Colorado)
 * 1104) Old North End Historic District (Columbus, Ohio)
 * 1105) Old North Knoxville
 * 1106) Old North Tower, University of Central Oklahoma
 * 1107) Old Northside Historic District
 * 1108) Old Northwood Historic District
 * 1109) Old Nueces County Courthouse
 * 1110) Old Oak
 * 1111) Old Ohavi Zedek Synagogue
 * 1112) Old Orange County Courthouse (California)
 * 1113) Old Orange County Courthouse (North Carolina)
 * 1114) Old Orchard Beach Inn
 * 1115) Old Orchard Shoal Light
 * 1116) Old Oxford Mill
 * 1117) Old Ozaukee County Courthouse
 * 1118) Old Palm Beach Junior College Building
 * 1119) Old Palmetto Hotel
 * 1120) Old Parsonage
 * 1121) Old Pasadena
 * 1122) Old Pascagoula High School
 * 1123) Old People's Home (Omaha)
 * 1124) Old People's Home (Tampa, Florida)
 * 1125) Old Perry County Courthouse (Rome, Indiana)
 * 1126) Old Perry Post Office
 * 1127) Old Petaluma Opera House
 * 1128) Old Philadelphia Presbyterian Church
 * 1129) Old Pickens Jail
 * 1130) Old Pickens Presbyterian Church
 * 1131) Old Piedras River Aqueduct
 * 1132) Old Pike Inn
 * 1133) Old Pilgrim Baptist Church Cemetery and Kilgore Family Cemetery
 * 1134) Old Pine Church
 * 1135) Old Pine Street Station
 * 1136) Old Pinecrest Hotel
 * 1137) Old Pinellas County Courthouse
 * 1138) Old Piqua High School
 * 1139) Old Plat Historic District
 * 1140) Old Platte Clove Post Office
 * 1141) Old Plover Methodist Church
 * 1142) Old Point Comfort Light
 * 1143) Old Point Loma Lighthouse
 * 1144) Old Police Headquarters
 * 1145) Old Polk County Courthouse (Florida)
 * 1146) Old Port Columbus Terminal
 * 1147) Old Port of Portland, Maine
 * 1148) Old Portlock School No. 5
 * 1149) Old Post Office (Albany, New York)
 * 1150) Old Post Office (Albuquerque, New Mexico)
 * 1151) Old Post Office (Augusta, Maine)
 * 1152) Old Post Office (Biddeford, Maine)
 * 1153) Old Post Office (Buffalo, New York)
 * 1154) Old Post Office (Hot Springs, Arkansas)
 * 1155) Old Post Office (Iowa City, Iowa)
 * 1156) Old Post Office (Kirkwood, Delaware)
 * 1157) Old Post Office (Liberty, Maine)
 * 1158) Old Post Office (Oneonta, New York)
 * 1159) Old Post Office (Pullman, Washington)
 * 1160) Old Post Office (Rogers, Arkansas)
 * 1161) Old Post Office (Washington, D.C.)
 * 1162) Old Post Office (Watertown, South Dakota)
 * 1163) Old Post Office Block
 * 1164) Old Post Office Building (Brockton, Massachusetts)
 * 1165) Old Post Office Building (Lynn, Massachusetts)
 * 1166) Old Post Office Building and Customhouse (Little Rock, Arkansas)
 * 1167) Old Post Office and Courthouse (Auburn, New York)
 * 1168) Old Post Office and Customshouse (Key West, Florida)
 * 1169) Old Pottstown Historic District
 * 1170) Old Poughkeepsie YMCA
 * 1171) Old Presbyterian Church (Barnwell, South Carolina)
 * 1172) Old Presbyterian Church (Parker, Arizona)
 * 1173) Old Presbyterian Meeting House
 * 1174) Old Presque Isle Light
 * 1175) Old Prince Edward County Clerk's Office
 * 1176) Old Probst Church
 * 1177) Old Providence Church
 * 1178) Old Providence Presbyterian Church
 * 1179) Old Providence Stone Church
 * 1180) Old Public Library
 * 1181) Old Quaker Meeting House (Queens)
 * 1182) Old Queens
 * 1183) Old Randolph County Courthouse (Arkansas)
 * 1184) Old Rectory (Perrowville, Virginia)
 * 1185) Old Red Mill
 * 1186) Old Red Mill and Mill House
 * 1187) Old Redfield City Hall
 * 1188) Old Redwater Bridge
 * 1189) Old Richmond Historic District
 * 1190) Old Richmond Schoolhouse and Gymnasium
 * 1191) Old River Bridge
 * 1192) Old Riverton Inn
 * 1193) Old Roanoke County Courthouse
 * 1194) Old Rock House (Harpersville, Alabama)
 * 1195) Old Rock House (Moscow Mills, Missouri)
 * 1196) Old Rock House (Thomson, Georgia)
 * 1197) Old Rock School (Dodgeville, Wisconsin)
 * 1198) Old Rock School (Guntersville, Alabama)
 * 1199) Old Rock School (Prairie du Chien, Wisconsin)
 * 1200) Old Rockport High School
 * 1201) Old Rockport Hutterite Colony
 * 1202) Old Rockville High School and East School
 * 1203) Old Rondo Cemetery
 * 1204) Old Rose Tree Tavern
 * 1205) Old Rotation
 * 1206) Old Roycemore School building
 * 1207) Old Runnymede Church
 * 1208) Old Russell County Courthouse
 * 1209) Old Ryan Farm
 * 1210) Old Saco High School
 * 1211) Old Sacramento State Historic Park
 * 1212) Old Saint Hilary's Church
 * 1213) Old Saint John Nepomocene Cemetery, Wrought-Iron Cross Site
 * 1214) Old Saint Paul's Cemetery
 * 1215) Old Saints Peter and Paul Cemetery, Wrought-Iron Cross Site
 * 1216) Old Salem
 * 1217) Old Salem Church and Cemetery
 * 1218) Old San Antonio City Cemeteries Historic District
 * 1219) Old San Antonio Hospital
 * 1220) Old San Francisco Mint
 * 1221) Old San Juan
 * 1222) Old Santa Rosa Catholic Church and Cemetery
 * 1223) Old Santa Susana Stage Road
 * 1224) Old Saratoga Reformed Church
 * 1225) Old Sardinia Town Hall
 * 1226) Old Savonoski Site
 * 1227) Old Saybrook South Green
 * 1228) Old Scarborough High School
 * 1229) Old School Baptist Church and Cemetery
 * 1230) Old School Baptist Church of Halcottsville
 * 1231) Old School House (Tampa, Florida)
 * 1232) Old School Privy
 * 1233) Old School Square
 * 1234) Old Schoolhouse (York, Maine)
 * 1235) Old Schoolhouse Bridge
 * 1236) Old Schwamb Mill
 * 1237) Old Scituate Light
 * 1238) Old Scotch Church
 * 1239) Old Scots Burying Ground
 * 1240) Old Scott County Jail
 * 1241) Old Scottish Rite Hospital building
 * 1242) Old Scripps Building
 * 1243) Old Searcy County Jail
 * 1244) Old Sebastian County Jail
 * 1245) Old Second National Bank
 * 1246) Old Seminary Building
 * 1247) Old Settler's Irrigation Ditch
 * 1248) Old Settler's Pavilion
 * 1249) Old Settlers' Association Park and Rhodham Bonnifield House
 * 1250) Old Settlers' Association of Johnson County Cabins
 * 1251) Old Settlers' Burying Ground
 * 1252) Old Shandon Historic District
 * 1253) Old Shelby County Courthouse
 * 1254) Old Sheldon Church Ruins
 * 1255) Old Shephard Farm
 * 1256) Old Ship African Methodist Episcopal Zion Church
 * 1257) Old Ship Church
 * 1258) Old Ship Street Historic District
 * 1259) Old Shipbuilder's Historic District
 * 1260) Old Silk Stocking Neighborhood
 * 1261) Old Sinclair Station
 * 1262) Old Sitka Site
 * 1263) Old Slave Mart
 * 1264) Old Sloatsburg Cemetery
 * 1265) Old Somersworth High School
 * 1266) Old Sopchoppy High School Gymnasium
 * 1267) Old South Church
 * 1268) Old South Church (Kirtland, Ohio)
 * 1269) Old South Mebane Historic District
 * 1270) Old South Meeting House
 * 1271) Old South Union Church
 * 1272) Old Southeast Church (Brewster, New York)
 * 1273) Old Southeast Town Hall
 * 1274) Old Southport High School
 * 1275) Old Spanish Fort (Pascagoula, Mississippi)
 * 1276) Old Spanish Trail (trade route)
 * 1277) Old Spink Colony
 * 1278) Old Spring Tavern
 * 1279) Old Springdale High School
 * 1280) Old St. Anastasia Catholic School
 * 1281) Old St. Andrew's Episcopal Church
 * 1282) Old St. Andrew's Parish Church
 * 1283) Old St. Anthony's Catholic Church (Violet, Texas)
 * 1284) Old St. Ferdinand Shrine
 * 1285) Old St. Gabriel's Episcopal Church
 * 1286) Old St. Helena Parish Jail
 * 1287) Old St. Johns County Jail
 * 1288) Old St. Joseph Hospital
 * 1289) Old St. Joseph's Catholic Church
 * 1290) Old St. Luke's Episcopal Church (Belton, Texas)
 * 1291) Old St. Luke's Hospital
 * 1292) Old St. Mary's Catholic Parish House
 * 1293) Old St. Mary's Cemetery, Wrought-Iron Cross Site
 * 1294) Old St. Mary's Church (Cincinnati, Ohio)
 * 1295) Old St. Mary's Church (Milwaukee, Wisconsin)
 * 1296) Old St. Mary's Church (Tempe, Arizona)
 * 1297) Old St. Nicholas Russian Orthodox Church
 * 1298) Old St. Patrick's Church (Chicago)
 * 1299) Old St. Patrick's Church (Gravois Mills, Missouri)
 * 1300) Old St. Paul's Methodist Episcopal Church
 * 1301) Old St. Peter's Church (Van Cortlandtville, New York)
 * 1302) Old St. Peter's Landmark
 * 1303) Old St. Raymond's Church
 * 1304) Old St. Teresa Catholic Church
 * 1305) Old St. Wenceslaus Catholic Parish House
 * 1306) Old Stagecoach Stop
 * 1307) Old State Bank (Decatur, Alabama)
 * 1308) Old State Bank (Vincennes, Indiana)
 * 1309) Old State Capitol (Kentucky)
 * 1310) Old State Capitol (Milledgeville, Georgia)
 * 1311) Old State Capitol State Historic Site
 * 1312) Old State House (Boston)
 * 1313) Old State House (Connecticut)
 * 1314) Old State House (Dover, Delaware)
 * 1315) Old State House (Little Rock, Arkansas)
 * 1316) Old State House (Providence, Rhode Island)
 * 1317) Old State Mutual Building
 * 1318) Old State Quarry State Preserve
 * 1319) Old State Road Bridge
 * 1320) Old Statehouse Historic District (Frankfort, Kentucky)
 * 1321) Old Stone Arch (Marshall, Illinois)
 * 1322) Old Stone Arch Bridge (Bound Brook, New Jersey)
 * 1323) Old Stone Arch Bridge (Clark Center, Illinois)
 * 1324) Old Stone Arch Bridge (Lewistown, Pennsylvania)
 * 1325) Old Stone Barracks
 * 1326) Old Stone Blacksmith Shop
 * 1327) Old Stone Church (Buffalo, North Dakota)
 * 1328) Old Stone Church (Chesterfield, Missouri)
 * 1329) Old Stone Church (Cleveland, Ohio)
 * 1330) Old Stone Church (Kingwood Township, New Jersey)
 * 1331) Old Stone Church (Lewisburg, West Virginia)
 * 1332) Old Stone Church (West Boylston, Massachusetts)
 * 1333) Old Stone Church (White Hall, Virginia)
 * 1334) Old Stone Church (Winchester, Virginia)
 * 1335) Old Stone Church Archeological Site
 * 1336) Old Stone Church and Cemetery
 * 1337) Old Stone Congregational Church
 * 1338) Old Stone Fort (Schoharie, New York)
 * 1339) Old Stone Fort (Tennessee)
 * 1340) Old Stone Hotel
 * 1341) Old Stone House (Brooklyn)
 * 1342) Old Stone House (Millboro Springs, Virginia)
 * 1343) Old Stone House (Morgantown, West Virginia)
 * 1344) Old Stone House (Pennsboro, West Virginia)
 * 1345) Old Stone House (Vale, Oregon)
 * 1346) Old Stone House (Washington, D.C.)
 * 1347) Old Stone House (Winnsboro, South Carolina)
 * 1348) Old Stone House (Winooski, Vermont)
 * 1349) Old Stone House Library
 * 1350) Old Stone Row
 * 1351) Old Stone Shop
 * 1352) Old Stone Tavern (Atkins, Virginia)
 * 1353) Old Stone Tavern (Frankfort, Kentucky)
 * 1354) Old Stone Tavern (Little Creek, Delaware)
 * 1355) Old Stone Tavern (Moorefield, West Virginia)
 * 1356) Old Stone Warehouse (Rochester, New York)
 * 1357) Old Stone Wharf Archeological Site
 * 1358) Old Storm Lake High School
 * 1359) Old Strother Place
 * 1360) Old Sugar Mill of Koloa
 * 1361) Old Sullivan County Courthouse
 * 1362) Old Sussex County Courthouse
 * 1363) Old Sutton High School
 * 1364) Old Talbott Tavern
 * 1365) Old Tampa Children's Home
 * 1366) Old Tarpon Springs City Hall
 * 1367) Old Tarpon Springs High School
 * 1368) Old Tavern (Burlington, Maine)
 * 1369) Old Tavern (Sacramento, California)
 * 1370) Old Tavern Farm
 * 1371) Old Taylor County Jail
 * 1372) Old Thames Shipyard
 * 1373) Old Third District Courthouse
 * 1374) Old Thomas James Store
 * 1375) Old Timbers
 * 1376) Old Todd County Courthouse
 * 1377) Old Tombstone
 * 1378) Old Town (Franklin, Tennessee)
 * 1379) Old Town Bridge (Franklin, Tennessee)
 * 1380) Old Town Bridge (Wayland, Massachusetts)
 * 1381) Old Town Cemetery (Newburgh, New York)
 * 1382) Old Town Center Historic District
 * 1383) Old Town College Park
 * 1384) Old Town Eureka
 * 1385) Old Town Farm
 * 1386) Old Town Fort Collins
 * 1387) Old Town Friends' Meetinghouse
 * 1388) Old Town Green Historic District
 * 1389) Old Town Hall (Athol, Massachusetts)
 * 1390) Old Town Hall (Chester, Connecticut)
 * 1391) Old Town Hall (Pittsfield, Massachusetts)
 * 1392) Old Town Hall (Stamford, Connecticut)
 * 1393) Old Town Hall (Tyngsborough, Massachusetts)
 * 1394) Old Town Hall (Wilmington, Delaware)
 * 1395) Old Town Hall Historic District (Duxbury, Massachusetts)
 * 1396) Old Town Hall Historic District (Huntington, New York)
 * 1397) Old Town Hall and School
 * 1398) Old Town Historic District (Ames, Iowa)
 * 1399) Old Town Historic District (Clearfield, Pennsylvania)
 * 1400) Old Town Historic District (Harrisonburg, Virginia)
 * 1401) Old Town Historic District (Hartford, Kentucky)
 * 1402) Old Town Historic District (Huntsville, Alabama)
 * 1403) Old Town Historic District (North Attleborough, Massachusetts)
 * 1404) Old Town Historic District (Selma, Alabama)
 * 1405) Old Town House (Marblehead, Massachusetts)
 * 1406) Old Town House (Parsonsfield, Maine)
 * 1407) Old Town House (Union, Maine)
 * 1408) Old Town Main Post Office
 * 1409) Old Town Manassas
 * 1410) Old Town Plantation
 * 1411) Old Town Residential Historic District (Las Vegas, New Mexico)
 * 1412) Old Town San Diego State Historic Park
 * 1413) Old Town Savings Bank
 * 1414) Old Town Sebastian Historic District, East
 * 1415) Old Town Sebastian Historic District, West
 * 1416) Old Town of Flushing Burial Ground
 * 1417) Old Town, Chicago
 * 1418) Old Town, Lansing, Michigan
 * 1419) Old Towne, Orange Historic District
 * 1420) Old Trail School (Wiggins, Colorado)
 * 1421) Old Trails Bridge
 * 1422) Old Trees
 * 1423) Old Turner Place
 * 1424) Old Turrell City Hall
 * 1425) Old U.S. Forest Products Laboratory
 * 1426) Old U.S. Post Office (Bend, Oregon)
 * 1427) Old U.S. Post Office (Marion, Ohio)
 * 1428) Old U.S. Post Office (Niles, Michigan)
 * 1429) Old U.S. Post Office (Ripley, Mississippi)
 * 1430) Old U.S. Post Office (Williston, North Dakota)
 * 1431) Old U.S. Route 79 (Kingsland, Arkansas)
 * 1432) Old US 41–Backwater Creek Bridge
 * 1433) Old US 67 Rest Area
 * 1434) Old Union Church and Cemetery
 * 1435) Old Union County Courthouse (Georgia)
 * 1436) Old Union County Courthouse (Pennsylvania)
 * 1437) Old Union County Jail (Blairsville, Georgia)
 * 1438) Old Union Depot Hotel
 * 1439) Old Union Meetinghouse
 * 1440) Old Union Methodist Church
 * 1441) Old Union School (Birdell, Arkansas)
 * 1442) Old Union School (Chesterville, Ohio)
 * 1443) Old Union School (Coshocton, Ohio)
 * 1444) Old United States Courthouse and Post Office (Frankfort, Kentucky)
 * 1445) Old United States Customshouse and Post Office and Fireproof Storage Company Warehouse
 * 1446) Old United States Post Office (Philadelphia, Mississippi)
 * 1447) Old United States Post Office and Courthouse (Miami, Florida)
 * 1448) Old United States Post Office and Courts Building (Jefferson, Texas)
 * 1449) Old University Library
 * 1450) Old University of Alabama Observatory
 * 1451) Old Upper Springfield Friends Burying Ground
 * 1452) Old Uptown Historic District (Harrisburg)
 * 1453) Old Urban Cemetery
 * 1454) Old Ursuline Convent, New Orleans
 * 1455) Old Vanderburgh County Courthouse
 * 1456) Old Vatia
 * 1457) Old Vero Beach Community Building
 * 1458) Old Vicksburg Bridge
 * 1459) Old Village Historic District (Chatham, Massachusetts)
 * 1460) Old Village Historic District (Monroe, Michigan)
 * 1461) Old WRUF Radio Station
 * 1462) Old Wadena Historic District
 * 1463) Old Wakulla County Courthouse
 * 1464) Old Walnut Ridge Post Office
 * 1465) Old Wappingers Falls Village Hall
 * 1466) Old Warner Brothers Studio
 * 1467) Old Warren County Courthouse
 * 1468) Old Warren County Courthouse Complex
 * 1469) Old Warrick County Jail
 * 1470) Old Washington County Courthouse (Oklahoma)
 * 1471) Old Washington County Courthouse (Utah)
 * 1472) Old Washington County Library
 * 1473) Old Water and Electric Light Plant
 * 1474) Old Watertown High School
 * 1475) Old Waterville High School
 * 1476) Old Waterville Post Office
 * 1477) Old Watson Homestead House
 * 1478) Old Wayne County High School
 * 1479) Old Weber Implement and Automobile Company
 * 1480) Old Webster Meeting House
 * 1481) Old Webster Schoolhouse
 * 1482) Old Weir Stove Building
 * 1483) Old Welbourne Farm and Dulany Family Cemetery
 * 1484) Old West Austin Historic District
 * 1485) Old West Baltimore Historic District
 * 1486) Old West Church (Boston, Massachusetts)
 * 1487) Old West Church (Calais, Vermont)
 * 1488) Old West End District (Toledo, Ohio)
 * 1489) Old West End Historic District (Muncie, Indiana)
 * 1490) Old West Haven High School
 * 1491) Old West Palm Beach National Guard Armory
 * 1492) Old West Salem City Hall
 * 1493) Old West Side Historic District
 * 1494) Old West, Dickinson College
 * 1495) Old Westbrook High School
 * 1496) Old Westbury Gardens
 * 1497) Old Westfield Cemetery
 * 1498) Old Wethersfield
 * 1499) Old Whaler's Church (Sag Harbor)
 * 1500) Old White Church Cemetery
 * 1501) Old White County Courthouse
 * 1502) Old White Meeting House Ruins and Cemetery
 * 1503) Old White Mill
 * 1504) Old Wilkes County Jail
 * 1505) Old Willow Community Center
 * 1506) Old Wilson Historic District
 * 1507) Old Wing Mission
 * 1508) Old Winona Middle School
 * 1509) Old Winters Ranch/Winters Mansion
 * 1510) Old Woodruff High School (Woodruff, South Carolina)
 * 1511) Old World Third Street Historic District
 * 1512) Old Worth County Courthouse (Iowa)
 * 1513) Old Wye Church
 * 1514) Old Wythe Historic District
 * 1515) Old York Gaol
 * 1516) Old Zion Methodist Church
 * 1517) Olde Town Arvada
 * 1518) Olde Woolen Mill
 * 1519) Oldenburg Historic District
 * 1520) Oldfields
 * 1521) Oldham Methodist Church
 * 1522) Olds Hall
 * 1523) Olds, Wortman & King
 * 1524) Oldtown Covered Bridge
 * 1525) Oldwick Historic District
 * 1526) Ole Arilsen House
 * 1527) Ole Bohman House
 * 1528) Ole Carlson House
 * 1529) Ole Crogen Farm District
 * 1530) Ole K. Roe House
 * 1531) Ole and Polly Oleson Farmhouse
 * 1532) Olean Armory
 * 1533) Olean Public Library
 * 1534) Olean Railroad Depot
 * 1535) Olean School No. 10
 * 1536) Olema Lime Kilns
 * 1537) Olema Valley Dairy Ranches Historic District
 * 1538) Oleson Park Music Pavilion
 * 1539) Oley Township, Pennsylvania
 * 1540) Oliphant–Walker House
 * 1541) Olivas Adobe
 * 1542) Olive Branch High School (New Carlisle, Ohio)
 * 1543) Olive Branch Methodist Episcopal Church
 * 1544) Olive Branch Missionary Baptist Church
 * 1545) Olive Chapel African Methodist Episcopal Church
 * 1546) Olive Furnace
 * 1547) Olive Hill (Matoaca, Virginia)
 * 1548) Olive Hill station
 * 1549) Olive Hotel
 * 1550) Olive Jeanette
 * 1551) Olive Township District No. 1 School
 * 1552) Olive and Hurley Old School Baptist Church
 * 1553) Olivenhain Town Meeting Hall
 * 1554) Oliver A. Wickes House
 * 1555) Oliver Avenue Bridge
 * 1556) Oliver Barrett House
 * 1557) Oliver Blood House
 * 1558) Oliver Brewster House
 * 1559) Oliver Bronson House
 * 1560) Oliver Building (Billings, Montana)
 * 1561) Oliver Building (Chicago)
 * 1562) Oliver Chace's Thread Mill
 * 1563) Oliver Ellsworth Homestead
 * 1564) Oliver Filley House
 * 1565) Oliver G. Traphagen House
 * 1566) Oliver H. Bair Funeral Home
 * 1567) Oliver H. Hovda House
 * 1568) Oliver Hastings House
 * 1569) Oliver Hazard Perry Graded School
 * 1570) Oliver High School
 * 1571) Oliver Hill Building
 * 1572) Oliver House (Corning, Arkansas)
 * 1573) Oliver House (Wakefield, Massachusetts)
 * 1574) Oliver House, Toledo, Ohio
 * 1575) Oliver Hutchins House
 * 1576) Oliver Johnson's Woods Historic District
 * 1577) Oliver Kelley Farm
 * 1578) Oliver L. and Catherine Link House
 * 1579) Oliver Mill Park
 * 1580) Oliver Miller Homestead
 * 1581) Oliver O. Stokes House
 * 1582) Oliver P. Morton House
 * 1583) Oliver Rice House
 * 1584) Oliver Street Historic District
 * 1585) Oliver Sturges House
 * 1586) Oliver W. Mills House
 * 1587) Oliver Warner Farmstead
 * 1588) Oliver Wendell Holmes House
 * 1589) Oliver White Tavern
 * 1590) Oliver Whiting Homestead
 * 1591) Oliver Wight House
 * 1592) Oliver Wiswall House
 * 1593) Oliver Wolcott House
 * 1594) Oliver and Gertrude Lundquist House
 * 1595) Oliver and Lucy Bonnell Gothic Arch Roofed Barn
 * 1596) Oliver and Margaret Jeffrey House
 * 1597) Oliver's Gift (log canoe)
 * 1598) Oliver-Leming House
 * 1599) Oliver–Eakle–Barfield Building
 * 1600) Oliver–Morton Farm
 * 1601) Olivet Chapel
 * 1602) Olivet Presbyterian Church
 * 1603) Olivet United Methodist Church, Parsonage and School
 * 1604) Olivia Apartments
 * 1605) Oljato Trading Post
 * 1606) Ollinger-Cobb House
 * 1607) Olmstead Place State Park
 * 1608) Olmstead Street Historic District
 * 1609) Olmstead station
 * 1610) Olmsted Family Farmhouse
 * 1611) Olmsted Station Powerhouse
 * 1612) Olmsted Subdivision Historic District
 * 1613) Olmsted-Hixon-Albion Block
 * 1614) Olney (Joppa, Maryland)
 * 1615) Olney Carnegie Library
 * 1616) Olney Cook Artisan Shop
 * 1617) Olney Elementary School
 * 1618) Olney Friends School
 * 1619) Olney High School
 * 1620) Olney Street–Alumni Avenue Historic District
 * 1621) Olof Johnson House
 * 1622) Olompali State Historic Park
 * 1623) Olsen House (Helena, Montana)
 * 1624) Olson House (Cushing, Maine)
 * 1625) Oltjenbruns Farm
 * 1626) Oluf Larsen House
 * 1627) Olustee Battlefield Historic State Park
 * 1628) Olympia Apartments (Washington, D.C.)
 * 1629) Olympia Armory
 * 1630) Olympia Downtown Historic District
 * 1631) Olympia Fields Country Club
 * 1632) Olympia Mill
 * 1633) Olympia School
 * 1634) Olympia Theater (Miami)
 * 1635) Olympic Apartment Building
 * 1636) Olympic Avenue Bridge
 * 1637) Olympic Cereal Mill
 * 1638) Olympic Club Hotel
 * 1639) Olympic National Park Headquarters Historic District
 * 1640) Olympus Guard Station
 * 1641) Olzie Whitehead Williams House
 * 1642) Omaha Bolt, Nut and Screw Building
 * 1643) Omaha Central High School
 * 1644) Omaha Ford Motor Company Assembly Plant
 * 1645) Omaha Hotel
 * 1646) Omaha National Bank Building
 * 1647) Omaha Public Library (building)
 * 1648) Omaha Quartermaster Depot Historic District
 * 1649) Omaha Rail and Commerce Historic District
 * 1650) Omaha Star building
 * 1651) Omaha Union Station
 * 1652) Omaha station (Chicago, Burlington and Quincy Railroad)
 * 1653) Omar Chapel
 * 1654) Omega Chapter of the Chi Phi Fraternity
 * 1655) Omena Historic District
 * 1656) Omni Bedford Springs Resort
 * 1657) Omni William Penn Hotel
 * 1658) Omohundro Water Treatment Plant
 * 1659) Omro Village Hall and Engine House
 * 1660) On the Hill (Boydton, Virginia)
 * 1661) Onancock Historic District
 * 1662) Onawa IOOF Opera House
 * 1663) Onawa Public Library
 * 1664) Onaway State Park
 * 1665) Onderdonk House
 * 1666) One Calvert Plaza
 * 1667) One Charles Center
 * 1668) One Main Place (Dallas)
 * 1669) One Moody Plaza
 * 1670) One North LaSalle
 * 1671) One Pendleton Place
 * 1672) One Thirty North Eighth Building
 * 1673) One-Million-Liter Test Sphere
 * 1674) Oneida Armory
 * 1675) Oneida Community Mansion House
 * 1676) Oneida Cotton Mills and Scott-Mebane Manufacturing Company Complex
 * 1677) Oneida County Courthouse (Idaho)
 * 1678) Oneida County Courthouse (Wisconsin)
 * 1679) Oneida Lake Congregational Church
 * 1680) Oneida Milling and Elevator Company Grain Elevator
 * 1681) Oneida Stake Academy
 * 1682) Oneida Street Station
 * 1683) Oneonta Armory
 * 1684) Oneonta Downtown Historic District
 * 1685) Oneonta Theatre
 * 1686) Onesquethaw Valley Historic District
 * 1687) Ongeluluul
 * 1688) Onion Creek Bridge (Coffeyville, Kansas)
 * 1689) Onion Portage Archeological District
 * 1690) Onon B. and Betsy Dahle House
 * 1691) Onondaga Highlands–Swaneola Heights Historic District
 * 1692) Onondaga Park
 * 1693) Onota, Au Train Township, Michigan
 * 1694) Onslow Gilmore House
 * 1695) Ontario Apartments
 * 1696) Ontario Heritage Square
 * 1697) Ontario State Bank Block
 * 1698) Ontario and Livingston Mutual Insurance Office
 * 1699) Ontario station (Oregon)
 * 1700) Onteora Park Historic District
 * 1701) Ontonagon County Courthouse
 * 1702) Ontonagon Harbor Piers Historic District
 * 1703) Ontonagon Light
 * 1704) Ontonagon School
 * 1705) Onyx Cave (Newburg, Missouri)
 * 1706) Oolenoy Baptist Church Cemetery
 * 1707) Ooten House
 * 1708) Opa-locka Bank
 * 1709) Opa-locka Company administration building
 * 1710) Opa-locka station
 * 1711) Opal's Steak House
 * 1712) Opana Radar Site
 * 1713) Opatrny Village Site
 * 1714) Opelousas Historic District
 * 1715) Open Air School (Columbus, Ohio)
 * 1716) Opequon Golf Club
 * 1717) Opequon Historic District
 * 1718) Opequon Presbyterian Church
 * 1719) Opera Block
 * 1720) Opera Hall Block (King City, Missouri)
 * 1721) Opera House and Yates Bookshop Building
 * 1722) Opera House at Boothbay Harbor
 * 1723) Opera House–Starnes Jewelers Building
 * 1724) Operation Crossbow Site
 * 1725) Operation Elster
 * 1726) Operations and Checkout Building
 * 1727) Ophir Town Hall
 * 1728) Opp Cottage
 * 1729) Oppenheim and St. Johnsville Union Society Church
 * 1730) Opposition House
 * 1731) Opus 40
 * 1732) Oquawka Wagon Bridge
 * 1733) Oquirrh School
 * 1734) Oquossoc Log Church
 * 1735) Ora Adams House
 * 1736) Ora Blanchard House
 * 1737) Ora Holland House
 * 1738) Ora Pelton House
 * 1739) Oracle State Park
 * 1740) Oracle Union Church
 * 1741) Oradell station
 * 1742) Oraibi, Arizona
 * 1743) Oram Nincehelser House
 * 1744) Oran Community Church
 * 1745) Oran District No. 22 Schoolhouse
 * 1746) Orange Armory
 * 1747) Orange Center Historic District (Orange, Connecticut)
 * 1748) Orange Center Historic District (Orange, Massachusetts)
 * 1749) Orange City Historic District
 * 1750) Orange City Town Hall
 * 1751) Orange Commercial Historic District
 * 1752) Orange County Courthouse (Indiana)
 * 1753) Orange County Courthouse (Virginia)
 * 1754) Orange Cove station (Atchison, Topeka and Santa Fe Railway)
 * 1755) Orange Grove (Dalzell, South Carolina)
 * 1756) Orange Grove Court
 * 1757) Orange Grove Plantation (Saint Helena Island, South Carolina)
 * 1758) Orange Grove Plantation House (Terrebonne Parish, Louisiana)
 * 1759) Orange Hall (St. Marys, Georgia)
 * 1760) Orange High School (Orange, California)
 * 1761) Orange High School (Orange, Virginia)
 * 1762) Orange Mill Historic District
 * 1763) Orange Park Elementary School
 * 1764) Orange Park Negro Elementary School
 * 1765) Orange Public Library
 * 1766) Orange Springs
 * 1767) Orange Springs Methodist Episcopal Church and Cemetery
 * 1768) Orange Street Historic District
 * 1769) Orange Street Presbyterian Church
 * 1770) Orange Street School
 * 1771) Orange Vale
 * 1772) Orange and Alexandria Railroad Bridge Piers
 * 1773) Orange and Alexandria Railroad Hooff's Run Bridge
 * 1774) Orange station (NJ Transit)
 * 1775) Orangeburg City Cemetery
 * 1776) Orangeburg County Fair Main Exhibit Building
 * 1777) Orangeburg County Jail
 * 1778) Orangeburg Downtown Historic District
 * 1779) Orators Mound
 * 1780) Orchard Beach State Park
 * 1781) Orchard House
 * 1782) Orchard Park station
 * 1783) Orchard Street United Methodist Church
 * 1784) Orchestra Hall (Detroit)
 * 1785) Oregon Caves Chateau
 * 1786) Oregon Caves Historic District
 * 1787) Oregon City Bridge
 * 1788) Oregon City Carnegie Library
 * 1789) Oregon City Municipal Elevator
 * 1790) Oregon Commercial Company Building
 * 1791) Oregon Commercial Historic District
 * 1792) Oregon Cracker Company Building
 * 1793) Oregon Creek Covered Bridge
 * 1794) Oregon Electric Railway Passenger Station
 * 1795) Oregon Film Museum
 * 1796) Oregon Hill
 * 1797) Oregon Historic District
 * 1798) Oregon Inlet Station
 * 1799) Oregon Iron Company Furnace
 * 1800) Oregon Masonic Hall (Oregon, Wisconsin)
 * 1801) Oregon Mill Complex
 * 1802) Oregon Pacific Railroad (1880–1894)
 * 1803) Oregon Portland Cement Building
 * 1804) Oregon Public Library
 * 1805) Oregon Railway and Navigation Company Bridge
 * 1806) Oregon Route 242
 * 1807) Oregon Shortline Railroad Company Building
 * 1808) Oregon State Bank Building
 * 1809) Oregon State Capitol
 * 1810) Oregon State Fair
 * 1811) Oregon State Forester's Office Building
 * 1812) Oregon State Hospital Historic District
 * 1813) Oregon State Soldier's Home Hospital
 * 1814) Oregon State University
 * 1815) Oregon Supreme Court Building
 * 1816) Oregon Trail (Ada County, Idaho segment)
 * 1817) Oregon Trail Ruts
 * 1818) Oregon Trail, Wells Springs Segment
 * 1819) Oregon Water Tower and Pump House
 * 1820) Oregon station (Illinois)
 * 1821) Orem's Delight
 * 1822) Oren F. and Adelia Parker House
 * 1823) Orenda/SP-26 Historic District, Chopawamsic RDA Camp 3
 * 1824) Orendorf Site
 * 1825) Orford Street Historic District
 * 1826) Orfordville Depot
 * 1827) Organ Cave
 * 1828) Orgonon
 * 1829) Orie J. Smith Black and White Stock Farm Historic District
 * 1830) Orient Baptist Church
 * 1831) Orient Bridge
 * 1832) Orient Historic District
 * 1833) Orient Manufacturing Company-Chadwick-Hoskins No. 3
 * 1834) Orient Point Light
 * 1835) Oriental Apartments
 * 1836) Oriental Building Association No. 6 Building
 * 1837) Oriental Lodge No. 500
 * 1838) Oriental Mills
 * 1839) Oriental Textile Mill
 * 1840) Oriental Theater (Denver)
 * 1841) Oriental Theatre (Milwaukee)
 * 1842) Orient–Fosterville Border Crossing
 * 1843) Original Church of God (Pulaski, Tennessee)
 * 1844) Original Congregational Church of Wrentham
 * 1845) Original Highlands, Louisville
 * 1846) Original Main Street Historic District
 * 1847) Original Newburgh Historic District
 * 1848) Original Springs Hotel and Bathhouse
 * 1849) Original Town of Fernandina Historic Site
 * 1850) Original Townsite Historic District
 * 1851) Original Wasco County Courthouse
 * 1852) Orin Clark House
 * 1853) Orin Jordan House
 * 1854) Orin Savage Cottage
 * 1855) Orion Clemens House
 * 1856) Oriskany Battlefield State Historic Site
 * 1857) Orkney Springs Hotel
 * 1858) Orland P. Bassett House
 * 1859) Orlando (Andover, Massachusetts)
 * 1860) Orlando Brice House
 * 1861) Orlando H. and Emma H. Hardcastle House
 * 1862) Orlando Health/Amtrak station
 * 1863) Orlando Humason House
 * 1864) Orlando Utilities Commission Administration Building
 * 1865) Orlando W. Warner House
 * 1866) Orlean Historic District
 * 1867) Orleans County Courthouse Historic District
 * 1868) Orleans County Courthouse and Jail Complex
 * 1869) Orleans Historic District
 * 1870) Orman-Adams House
 * 1871) Ormond Fire House
 * 1872) Ormond Hotel
 * 1873) Ormond Plantation House
 * 1874) Ormond Yacht Club
 * 1875) Ormonde (Cazenovia, New York)
 * 1876) Ormonde Apartment Building
 * 1877) Ormsby-Kelly House
 * 1878) Ormsby-Laughlin Textile Companies Mill
 * 1879) Ormsby–Rosser House
 * 1880) Orna Villa
 * 1881) Orndoff-Cross House
 * 1882) Orne Covered Bridge
 * 1883) Orofino Historic District
 * 1884) Orono Main Street Historic District
 * 1885) Orono Post Office
 * 1886) Orosi Branch Library
 * 1887) Orote Field
 * 1888) Orote Historical Complex
 * 1889) Oroville Carnegie Library
 * 1890) Oroville Chinese Temple
 * 1891) Orpheum Lofts
 * 1892) Orpheum Theater (New Orleans)
 * 1893) Orpheum Theater (Sioux Falls)
 * 1894) Orpheum Theater (St. Louis)
 * 1895) Orpheum Theatre (Champaign, Illinois)
 * 1896) Orpheum Theatre (Madison, Wisconsin)
 * 1897) Orpheum Theatre (Memphis)
 * 1898) Orpheum Theatre (Minneapolis)
 * 1899) Orpheum Theatre (Omaha)
 * 1900) Orpheum Theatre (Phoenix, Arizona)
 * 1901) Orpheum Theatre (Sioux City, Iowa)
 * 1902) Orpheum Theatre (Wichita, Kansas)
 * 1903) Orr Iron Company
 * 1904) Orr Roadside Parking Area
 * 1905) Orr School
 * 1906) Orr-Herl Mound and Village Site
 * 1907) Orrin B. Hartley House
 * 1908) Orrin Hoadley House
 * 1909) Orrin Todd House
 * 1910) Orrin W. Burritt House
 * 1911) Orrin White House
 * 1912) Orrin and Roxanne Fairman Kinyon House
 * 1913) Orsel and Minnie McGhee House
 * 1914) Orson Ames House
 * 1915) Orson Everitt House
 * 1916) Orson Grimmett Bungalow
 * 1917) Orson Pratt House
 * 1918) Orson Rogers House
 * 1919) Ortega (Jacksonville)
 * 1920) Orth C. Galloway House
 * 1921) Orth House
 * 1922) Orthodox Meetinghouse
 * 1923) Ortiz House (Yuma, Arizona)
 * 1924) Orton Memorial Laboratory
 * 1925) Orton Park
 * 1926) Orton Park Historic District
 * 1927) Orton Plantation
 * 1928) Ortonville Mill
 * 1929) Orvall Gammill Barn
 * 1930) Orville Beach Memorial Manual Training School
 * 1931) Orville Jackson House
 * 1932) Orville P. and Sarah Chubb House
 * 1933) Orville T. Waring House
 * 1934) Orvis Road Historic District
 * 1935) Orwell Site (Orwell, Vermont)
 * 1936) Orwell site (Fergus Falls, Minnesota)
 * 1937) Osage Bank of Fairfax
 * 1938) Osage Commercial Historic District
 * 1939) Osage County Courthouse (Kansas)
 * 1940) Osage County Poorhouse
 * 1941) Osage Farms Resettlement Properties in Pettis County, Missouri
 * 1942) Osage Mills Dam
 * 1943) Osage Mission Infirmary
 * 1944) Osage Village State Historic Site
 * 1945) Osborn Hotel
 * 1946) Osborn House
 * 1947) Osborn Street School
 * 1948) Osborne Homestead Museum
 * 1949) Osborne House (Victor, New York)
 * 1950) Osborne Public Carnegie Library
 * 1951) Osborne Wells House
 * 1952) Osborn–Bennett Historic District
 * 1953) Osborn–Bouton–Mead House
 * 1954) Oscar Anderson House Museum
 * 1955) Oscar Blomeen House
 * 1956) Oscar C. Diehl House
 * 1957) Oscar C. Woods House
 * 1958) Oscar Carlson House
 * 1959) Oscar Chambers House
 * 1960) Oscar Crow House
 * 1961) Oscar Easley Block
 * 1962) Oscar F. Lyons House
 * 1963) Oscar Foss Memorial Library
 * 1964) Oscar G. Johnson VA Medical Center
 * 1965) Oscar G. and Mary H. Burch House
 * 1966) Oscar Gill House
 * 1967) Oscar Hammerstein II Farm
 * 1968) Oscar Leibhart Site
 * 1969) Oscar Lindsay House
 * 1970) Oscar M. Booth House
 * 1971) Oscar Nichols House
 * 1972) Oscar Redman Building
 * 1973) Oscar Roeser House
 * 1974) Oscar Stanton De Priest House
 * 1975) Oscar Taylor House
 * 1976) Oscar W. Underwood House
 * 1977) Oscar and Christina Beckman Farmstead
 * 1978) Oscar-Zero Missile Alert Facility
 * 1979) Osceola Apartment Hotel
 * 1980) Osceola Commercial Historic District
 * 1981) Osceola County Courthouse (Florida)
 * 1982) Osceola County Courthouse (Iowa)
 * 1983) Osceola Ditch
 * 1984) Osceola Park Historic Residential District
 * 1985) Osceola Public School Building
 * 1986) Osceola Times Building
 * 1987) Osceola Town Hall
 * 1988) Osceola station
 * 1989) Osceola station (Wisconsin)
 * 1990) Osgood Bradley Building
 * 1991) Osgood Building
 * 1992) Osgood Ditch
 * 1993) Osgood Family House
 * 1994) Osgood Farm
 * 1995) Osgood Gamekeeper's Lodge
 * 1996) Osgood Hill
 * 1997) Osgood–Kuhnhausen House
 * 1998) Oshkosh Grand Opera House
 * 1999) Oshkosh Northwestern
 * 2000) Oshkosh Water Tower
 * 2001) Oshtemo Town Hall
 * 2002) Oskaloosa City Hall
 * 2003) Oskaloosa City Park and Band Stand
 * 2004) Oskaloosa City Square Commercial Historic District
 * 2005) Oskaloosa Fire Station
 * 2006) Oskaloosa Monthly Meeting of Friends Parsonage
 * 2007) Oskaloosa Post Office
 * 2008) Oskaloosa Public Library
 * 2009) Oskaloosa station
 * 2010) Oskar G. Stonorov House
 * 2011) Osmund Osmundson House
 * 2012) Osmyn and Emily Deuel House
 * 2013) Osprey School
 * 2014) Osprey Site
 * 2015) Ossabaw Island
 * 2016) Osseo Water Tower
 * 2017) Ossian H. Sweet House
 * 2018) Ossian Opera House
 * 2019) Ossian Wilbur Goss Reading Room
 * 2020) Ossoli Circle
 * 2021) Ost Valle Bridge
 * 2022) Osterburg Covered Bridge
 * 2023) Osterhoudt Stone House
 * 2024) Osterman and Tremaine Building
 * 2025) Osterville Baptist Church
 * 2026) Oswald J. Nitschke House
 * 2027) Oswegatchie Historic District
 * 2028) Oswegatchie Pumping Station
 * 2029) Oswego Armory
 * 2030) Oswego City Hall
 * 2031) Oswego City Library
 * 2032) Oswego County Courthouse
 * 2033) Oswego Harbor West Pierhead Light
 * 2034) Oswego Meeting House and Friends' Cemetery
 * 2035) Oswego Public Library
 * 2036) Oswego Theater
 * 2037) Oswego United States Post Office
 * 2038) Oswego Yacht Club
 * 2039) Oswego–Oneida Streets Historic District
 * 2040) Oteen Veterans Administration Hospital Historic District
 * 2041) Otero's 66 Service
 * 2042) Otha Walker Homestead
 * 2043) Other C. Wamsley House
 * 2044) Othniel Looker House
 * 2045) Otho Poole House
 * 2046) Otis Angell Gristmill
 * 2047) Otis Cary House
 * 2048) Otis Center Historic District
 * 2049) Otis Company Mill No. 1
 * 2050) Otis Elevator Company Building (Portland, Oregon)
 * 2051) Otis Elevator Company Factory Building
 * 2052) Otis Hare Archeological Site
 * 2053) Otis Hotel
 * 2054) Otis L. Brown House
 * 2055) Otis Park and Golf Course
 * 2056) Otis Putnam House
 * 2057) Otis Starkey House
 * 2058) Otis Theodore and Effiegene Locke Wingo House
 * 2059) Otis-Wyman House
 * 2060) Otoe County Courthouse
 * 2061) Otowi Historic District
 * 2062) Otowi Suspension Bridge
 * 2063) Otranto Plantation
 * 2064) Otranto Plantation Indigo Vats
 * 2065) Otsdawa Baptist Church
 * 2066) Otsego Apartments
 * 2067) Otsego County Courthouse
 * 2068) Ott's Assay Office
 * 2069) Ott's Chapel
 * 2070) Ottari Sanitarium
 * 2071) Ottauquechee River Bridge
 * 2072) Ottawa (tug)
 * 2073) Ottawa Beach Historic District
 * 2074) Ottawa Commercial Historic District
 * 2075) Ottawa East Side Historic District
 * 2076) Ottawa High School and Junior High School
 * 2077) Ottawa Library (Kansas)
 * 2078) Ottawa Street Power Station
 * 2079) Ottawa Waterworks Building
 * 2080) Ottendorfer Public Library and Stuyvesant Polyclinic Hospital
 * 2081) Otter Creek Archaeological Site (Ferrum, Virginia)
 * 2082) Otter Creek Bridge (Cedar Vale, Kansas)
 * 2083) Otter Creek Bridge (Oelwein, Iowa)
 * 2084) Otter Lake Community Church
 * 2085) Otter Spring House
 * 2086) Otter Tail County Courthouse
 * 2087) Otterbein Church (Baltimore, Maryland)
 * 2088) Otterbein Church (Evans, West Virginia)
 * 2089) Otterburn (Bedford, Virginia)
 * 2090) Otto Brinkmann House
 * 2091) Otto Carmichael House
 * 2092) Otto H. Baring House
 * 2093) Otto Huechling House
 * 2094) Otto J. Hager House
 * 2095) Otto Schlemmer Building
 * 2096) Otto Sr. and Lisette Hahn House
 * 2097) Otto W. and Ida L. Nelson House
 * 2098) Otto and Hilda Gretzinger House
 * 2099) Otto and Verdell Rutherford House
 * 2100) Ottumwa Cemetery
 * 2101) Ottumwa City Hall
 * 2102) Ottumwa Public Library
 * 2103) Ottumwa Regional Airport
 * 2104) Ottumwa Young Women's Christian Association
 * 2105) Ottumwa station
 * 2106) Otway Covered Bridge
 * 2107) Otway Henderson House
 * 2108) Otwell (Oxford, Maryland)
 * 2109) Ouachita Avenue Historic District
 * 2110) Ouachita County Courthouse
 * 2111) Ouachita Parish High School
 * 2112) Ouachita River Bridge (Arkadelphia, Arkansas)
 * 2113) Ouachita River Lock and Dam No. 8
 * 2114) Ouaquaga Lenticular Truss Bridge
 * 2115) Ouilmette North Historic District
 * 2116) Oulagisket
 * 2117) Our Lady Help of Christians Chapel (Cheektowaga, New York)
 * 2118) Our Lady Help of Christians Historic District (Newton, Massachusetts)
 * 2119) Our Lady of Good Voyage Church (Gloucester, Massachusetts)
 * 2120) Our Lady of Grace Church (Reserve, Louisiana)
 * 2121) Our Lady of Guadaloupe Church
 * 2122) Our Lady of Guadalupe Church (San Jose, California)
 * 2123) Our Lady of Guadalupe Church and Medina Cemetery
 * 2124) Our Lady of Limerick Catholic Church (Glenns Ferry, Idaho)
 * 2125) Our Lady of Loretto Roman Catholic Church and Cemetery
 * 2126) Our Lady of Lourdes Church (Victoria, Texas)
 * 2127) Our Lady of Lourdes Church Complex
 * 2128) Our Lady of Mercy Chapel
 * 2129) Our Lady of Mercy High School (Ohio)
 * 2130) Our Lady of Mount Carmel Grotto
 * 2131) Our Lady of Mt. Carmel Church
 * 2132) Our Lady of Perpetual Help Church (Altus, Arkansas)
 * 2133) Our Lady of Perpetual Help Roman Catholic Church
 * 2134) Our Lady of Purification Catholic Church
 * 2135) Our Lady of Sorrows Catholic Church (Rock Springs, Wyoming)
 * 2136) Our Lady of Sorrows Chapel
 * 2137) Our Lady of Sorrows Church (Bernalillo, New Mexico)
 * 2138) Our Lady of Sorrows Church (Las Vegas, New Mexico)
 * 2139) Our Lady of Victory Academy (Fort Worth, Texas)
 * 2140) Our Lady of Victory Catholic Church (Pearce, Arizona)
 * 2141) Our Lady of Victory Roman Catholic Church
 * 2142) Our Lady of the Angels Academy
 * 2143) Our Lady of the Angels School (Albuquerque, New Mexico)
 * 2144) Our Lady of the Annunciation Chapel at Annunciation Priory
 * 2145) Our Lady of the Assumption School
 * 2146) Our Lady of the Blessed Sacrament Church
 * 2147) Our Lady of the Ozarks Shrine
 * 2148) Our Lady of the Rosary Church (Detroit)
 * 2149) Our Lady of the Wayside Church
 * 2150) Our Lady, Queen of Heaven Church
 * 2151) Our Mother of Mercy Catholic Church and Parsonage
 * 2152) Our Mother of Sorrows Grotto Historic District
 * 2153) Our Mother of Sorrows Monastery and Retreat Center (West Springfield, Massachusetts)
 * 2154) Our Mother of Sorrows Roman Catholic Church Complex
 * 2155) Our Savior's Kvindherred Lutheran Church (Calamus, Iowa)
 * 2156) Our Savior's Lutheran Church (Menno, South Dakota)
 * 2157) Our Savior's Scandinavian Lutheran Church
 * 2158) Our Saviour's Evangelical Lutheran Church
 * 2159) Ourant's School
 * 2160) Ouray City Hall and Walsh Library
 * 2161) Ouray Historic District
 * 2162) Out-of-Door Academy
 * 2163) Outdoor Art Club
 * 2164) Outing Club
 * 2165) Outing Park Historic District
 * 2166) Outlands in the Eighty Acres
 * 2167) Outlaw Inn
 * 2168) Outlet Mound
 * 2169) Outlook station (Montana)
 * 2170) Over-the-Jumps Carousel
 * 2171) Over-the-Rhine
 * 2172) Overackers Corners Schoolhouse
 * 2173) Overbrook (Nashville, Tennessee)
 * 2174) Overbrook Elementary School
 * 2175) Overbrook Farms, Philadelphia
 * 2176) Overbrook High School (Philadelphia)
 * 2177) Overcarsh House
 * 2178) Overfield Tavern
 * 2179) Overholser Mansion
 * 2180) Overland Waterloo Company Building
 * 2181) Overlook (Little Falls, New York)
 * 2182) Overlook (Martinsburg, West Virginia)
 * 2183) Overlook Castle
 * 2184) Overlook Historic District
 * 2185) Overmyer–Waggoner–Roush Farm
 * 2186) Overseas Highway
 * 2187) Overstreet Hall
 * 2188) Overstreet House
 * 2189) Overton Corners–Lacolle 221 Border Crossing
 * 2190) Overton Farm
 * 2191) Overton Gymnasium
 * 2192) Overton Lane
 * 2193) Overton Park
 * 2194) Overtown Historic District
 * 2195) Oviatt House
 * 2196) Owasco Reformed Church
 * 2197) Owatonna Commercial Historic District
 * 2198) Owatonna Firemen's Hall
 * 2199) Owatonna Public Library
 * 2200) Owego Central Historic District
 * 2201) Owen A. and Emma J. Garretson House
 * 2202) Owen B. Pickett United States Custom House
 * 2203) Owen Building (Columbia, South Carolina)
 * 2204) Owen Chapel Church of Christ
 * 2205) Owen Coachman House
 * 2206) Owen County Courthouse (Indiana)
 * 2207) Owen County Courthouse and Jail
 * 2208) Owen E. LeFevre House
 * 2209) Owen Estate
 * 2210) Owen Family House and Cemetery
 * 2211) Owen High School
 * 2212) Owen Lovejoy House
 * 2213) Owen Martin House
 * 2214) Owen Moon Farm
 * 2215) Owen Park, Tulsa
 * 2216) Owen Plantation House
 * 2217) Owen Tudor Hedges House
 * 2218) Owen-Cox House
 * 2219) Owen-Gay Farm
 * 2220) Owen-Harrison House
 * 2221) Owen-Primm House
 * 2222) Owensville Historic District
 * 2223) Owens–Thomas House
 * 2224) Owings House
 * 2225) Owings Upper Mill
 * 2226) Owingsville Commercial District and Courthouse Square
 * 2227) Owl Blacksmith Shop
 * 2228) Owl's Bend Site
 * 2229) Owl's Head Historic District
 * 2230) Owl's Nest
 * 2231) Owl's Nest Country Place
 * 2232) Owls Head (Hebron, New Hampshire)
 * 2233) Owls Head Light
 * 2234) Owosso Downtown Historic District
 * 2235) Owsley Bridge
 * 2236) Owyhee County Courthouse
 * 2237) Owyhee Dam
 * 2238) Ox Bow Inn
 * 2239) Oxbow Archeological District
 * 2240) Oxbow Historic District
 * 2241) Oxford Commercial Historic District
 * 2242) Oxford Congregational Church and Cemetery
 * 2243) Oxford Courthouse Square Historic District
 * 2244) Oxford Downtown Historic District
 * 2245) Oxford Female Institute
 * 2246) Oxford Furnace
 * 2247) Oxford Historic District (Georgetown, Kentucky)
 * 2248) Oxford Historic District (Oxford, Georgia)
 * 2249) Oxford Historic District (Oxford, Maryland)
 * 2250) Oxford Historic District (Oxford, North Carolina)
 * 2251) Oxford Historic District (Oxford, Pennsylvania)
 * 2252) Oxford Hotel (Denver, Colorado)
 * 2253) Oxford Hotel (Oxford, Pennsylvania)
 * 2254) Oxford Hotel (West Baden Springs, Indiana)
 * 2255) Oxford House (Grand Forks, North Dakota)
 * 2256) Oxford Industrial Historic District
 * 2257) Oxford Main Street Historic District
 * 2258) Oxford Presbyterian Church
 * 2259) Oxford School (Fairhaven, Massachusetts)
 * 2260) Oxford Village Historic District
 * 2261) Oxford station (Baltimore and Ohio Railroad)
 * 2262) Oxford-Whitney Streets Historic District
 * 2263) Oxford–Crown Historic District
 * 2264) Oxley Barn
 * 2265) Oxmoor Farm
 * 2266) Oxnard Historic Farm Park
 * 2267) Oxon Cove Park and Oxon Hill Farm
 * 2268) Oxon Hill Manor
 * 2269) Oyster Bay station
 * 2270) Ozark Courthouse Square Historic District (Ozark, Arkansas)
 * 2271) Ozark Courthouse Square Historic District (Ozark, Missouri)
 * 2272) Ozark Iron Furnace Stack
 * 2273) Ozark Trails Marker at Lake Arthur
 * 2274) Ozark station (Arkansas)
 * 2275) Ozette Indian Village Archeological Site
 * 2276) Ozias Goodwin House
 * 2277) Ozmer House
 * 2278) Ozone School