Lumen Technologies Building

The Lumen Technologies Building in Minneapolis, Minnesota was completed in 1932 and became the tallest building to be built in the city during the 1930s, 1940s, and 1950s. Named for its current owner, it was previously known as the CenturyLink Building, Qwest Building and the Northwestern Bell Telephone Building. Originally standing 346 feet (105 m) tall, the structure grew to 416 feet (127 m) with the addition of a microwave antenna "crown" in 1958, followed by the addition of a second tier of microwave antennas in 1972. The antennas, which were used for AT&T Long Lines, were removed in 2019. It was the second-tallest building in the city after the slightly older Foshay Tower for many years, and stands slightly taller than the tower of its neighbor, Minneapolis City Hall.

The building has many small details on the exterior, including electric bolts and a stylized bird above the main entrance. When under construction, an unusual move was made by stripping a 1920s Northwestern Bell building on the site and the steel frame was incorporated into the new structure. The building was expanded on its west side in the 1940s.

History
Telephone service in Minneapolis first began in 1878 with a switchboard located in the old city hall, located in the Gateway area, and serving 11 phones. Demand increased rapidly, and in 1885, the central office had 775 lines and was moved to the second floor of the city hall building. In 1890, the office outgrew its quarters in the city hall, with 1700 lines, so it moved to a building on Fourth Street between Nicollet and Marquette Avenues. Demand increased to 3000 subscribers in 1897, so a three-story building was built at Third Avenue South and Fifth Street. In 1908, two five-story wings were built. Additional central office buildings were established outside downtown Minneapolis. By 1920, there were 96,000 telephones in 14 central office buildings.

In 1920, a nine-story building was built at Third Avenue South and Fifth Street. That building was planned with the possibility that it would be merged into a larger structure. In 1929, with still more expansion, six floors were leased in an outside building. Finally, the current building was built, after a study of future needs. It was decided to add some space for the Minnesota administrative offices of the phone company, in a decision that was both economical and architecturally pleasing.

When built, the building had its business office on the first floor, with space for customers to transact business with the phone company, public telephone booths, and rooms for long-distance calls. The next 12 floors contained telephone equipment, such as long-distance switchboards, other special switchboards, and dial central office equipment for the MAin, ATlantic, and BRidgeport central offices. There were also breakroom facilities and a lunch room for telephone operators who were off duty. The 14th, 25th, and 26th floors were mechanical floors. Finally, a tower on the 15th through 24th floors housed administrative offices of the telephone company. There were also three basement floors with power and heating equipment, along with cable vaults. The building measured 346 ft above street level, 42 ft in the basements, and had 26 stories. Many of these stories were somewhat taller than those in office buildings due to the size of central office equipment. The building had 24000 sqft of floor space, and housed about 1,000 employees.

Minnesota construction materials were used in the building, with a granite exterior from Morton on the first floor and limestone from Kasota on subsequent stories. Cement from Duluth and steel from the Mesabi Range were used for interior construction. The building was designed by Minnesota architects, built by Minneapolis contractors, and supplied with other materials by Minnesota firms.