1835 Market Street, formerly known as Eleven Penn Center, is a high-rise building located in the Market West region of Philadelphia, Pennsylvania. The building stands at 425 feet (130 meters) with 29 floors, and was completed in 1986. It is currently the 21st-tallest building in Philadelphia. 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.