Established as the county seat of Pickaway County in 1810, Circleville took its name from the circular portion of a large Hopewell-era earthwork on which it was built. The Circleville earthworks, described in 1772 by Rev. David Jones for a Boston magazine, consisted of an 1,100 foot diameter circle connected to a 900 foot square. Town director Daniel Dreisbach platted the town directly atop the earthworks, integrating the town plan into the prehistoric landscape, with an octagonal courthouse standing at the center. By the mid-1830s, dissatisfaction with Circleville's radial-concentric street layout led the Circleville Squaring Company, authorized by the State Assembly in 1837, to convert the town plan into a conventional grid, a process completed in several phases by 1856. Circleville holds a unique place in American town planning as both a later development of Native American engineering and the earliest known example of urban redevelopment in the United States.