6abc.com has a story, and it's also using phillyskyline.com as a source!
PHILADELPHIA - March 14, 2008 (WPVI) -- A world-class architectural firm has decided that things are looking up for Philadelphia ... about 1500 feet up.
The website Phillyskyline.com says the firm of Kohn Pederson Fox has unveiled a design for the American Commerce Center. It would rise to 89 stories from what is now a parking lot at 18th and Arch Streets, and would include offices, a hotel, and street-level stores.
The building, plus its spire, would be a full 525 feet taller than the Comcast Center, which is currently the tallest building in the city.
The designers hope to break ground next year.