Technically outside of Penn Center ( PH109), but related in time and design, are the twin poured-in-place concrete towers of Center Square. Given verticality by chamfered corners and joined by a shared glass-roofed galleria whose detail better suits the originally proposed stone facade, Center Square completed that firm's encircling of the west side of City Hall, largely replacing buildings that Frank Furness had executed in the previous century. Claes Oldenburg's splendid three-story Clothespin (as big as Penn on the top of City Hall; PH49) of rusted Corten steel with its stainless spring happily forming a 7 and a 6, acknowledges the nation's bicentennial while the juxtaposition of shapes was intended to recall Brancusi's famed sculpture The Kiss, which in turn suggested the city's nickname, “City of Brotherly Love.”
After World War II, city planner Edmund Bacon's quixotic “gentleman's agreement” to limit skyscrapers to the level of the base of the Penn statue atop City Hall led to a crewcut skyline that drained the energy from the city's tall buildings. In the 1980s, developer Willard Rouse, declaring that he was “no gentleman,” built the pair of skyscrapers that he called “Liberty Place” that soared over 400 feet above Penn to a peak of 961 feet. Others have followed, resulting in an array of iconic towers that enliven the skyline of the modern city.