1835 Market Street

1835 Market Street, formerly known as Eleven Penn Center (or 11 Penn Center), is a high-rise building located in the Market West region of Philadelphia. The building stands at 425 ft with 29 floors. Radnor Corp. the real estate arm of Sun Co. began development of the property in 1984. It opened in 1986 and Colonial Penn was one of the anchor tenants. The architectural firm who designed the building was the Kling Lindquist Partnership. 1835 Market Street is a part of Penn Center complex, which includes several notable skyscrapers such as the Mellon Bank Center and Five Penn Center.

It is currently the 24th-tallest building in Philadelphia.

Ownership
In 2002, a joint venture including the California State Teachers' Retirement System (CalSTRS) purchased the tower for US$80 million. CalSTRS sold it to Nightingale Group for US$100 million in 2014.