In 1999, class-A office vacancy in the city was at 6.6%, leading developer Willard Rouse to envision a new tower. Eventually the developer settled on the location where he constructed this building, a , $288 per square-foot parcel owned by Equitable Life Assurance Co. In 2000, the architect and Driehaus Prize winner Robert A. M. Stern began working on a design for a skyscraper being planned by Liberty Property Trust in Philadelphia, Pennsylvania. In 2001, Liberty Property Trust announced its plan to build the 52-story One Pennsylvania Plaza in Center City. Anticipated US$400 million, One Pennsylvania Plaza was to be and made of kasota stone similar to the Philadelphia Museum of Art. The site for the future skyscraper was at 17th Street and John F. Kennedy Boulevard, a site occupied by a building that housed the Defender Association of Philadelphia and a parking lot. Demolition of the building began in 2002 and ended in 2003.