宾夕法尼亚州费城市政中心，空中透视图

This drawing is one of a number of studies Kahn made in the 1950s of the historic downtown district in his long-time home of Philadelphia. In this small bird's-eye panorama, Kahn developed his idea of a city surrounded by massive cylindrical parking towers, defending the center—which he called the "Forum"—against an onslaught of automobiles and the forces of decentralization that threatened social interaction. The historical references that were beginning to emerge in his work are evinced by the gateway towers, which recall ancient monuments, like the Roman Colosseum, in various states of decay.