I just looked it up on Google maps. You can see the very spot it was taken from. 1126 North Front St. It's near the Girard subway stop. The sign is painted over, but the McD's sign is still there.
These are really well done. At least the Hancock building is rectangular. If I try this from the CN Tower in Toronto or the Sky Tower in Auckland, the curved observation area adds a lot of distortion.....unless the two images are only a couple of meters apart....