ABSTRACT
William Penn developed the plan of what is now known as center-city Philadel-
phia in the middle of the seventeenth century. Penn’s plan for Philadelphia, an
alloy of Quaker Utopianism and colonial real-estate speculation, is distinguished
not only for its influence as a prototype in the founding of subsequent Amer-
ican cities, but for the ways in which its basic outlines have continued to
endure in the form of the city’s historical center. Although not unique among
North American cities for having been established with a deliberate plan,
Philadelphia’s evolution over the past three centuries presents an singularly
important case through which to examine the interplay between the concepts
embodied in an originating plan, the material characteristics of the plan itself,
and the historical circumstances that transform, usurp or supersede that plan.
