131 Ponce de Leon Avenue, also known as the Gulf Oil Building, was both a building in Midtown Atlanta, at the southeast corner of Ponce de Leon Avenue and Juniper Street, as well as the name of a planned mixed-use development which would incorporate portions of the Pei building's façade and add 321 apartments and 8,600 square feet (800 m2) of retail space. The building was architect I. M. Pei's first project, built in 1949, a 50,000 square feet (4,600 m2) two-story "box that invoked the lean rectilinearity of Mies van der Rohe".