West Market Street - a district lined with most of the city's contributions to sky scraping architecture - was once home to a number of theaters, shops, apartments, and hotels facing Broad Street Station's "Chinese Wall". A long forgotten gem of this gritty, eclectic strip was the Harrison Building - demolished in 1969 along with the Arcade Building (the domed building in the rear).
At 4 South 15th, the Harrison Building served as an office building and hotel. It was designed by Cope & Stewardson in 1894, with alterations in 1902 and 1912, and razed in 1969 as part of West Market's massive urban renewal project which also included the demolition of Broad Street Station and the Arcade Building.
Centre Square, or rather the Clothes Pin itself, now occupies the site of the Harrison Building. Although many are coming to once again appreciate Brutalist architecture - and Comcast did a good job renovating the entrance to Centre Square, as well as the transportation plaza holding the Clothes Pin - I would love to have seen this brutal presence side by side with the elegant Harrison Building, not to mention the massive Frank Furness Arcade Building across 15th Street framing City Hall with its sister to the East, the Wanamaker Building.
Centre Square was designed by Vincent Kling & Associates in 1973.