Circleville was founded in 1810. It derived its name from the circular portion of a large Hopewell culture earthwork upon which it was built. The original town plan integrated Circleville into the preexisting land with a street layout of concentric circles. An octagonal courthouse stood directly in the center.
Dissatisfaction rose with Circleville's layout, however, and in 1837, the Ohio General Assembly authorized the "Circleville Squaring Company" to convert it into a square. By 1856, this had been completed in several phases. No remaining traces of the original earthworks remain, though a few old buildings retain curved walls that were part of the original circular layout.
I think that it's a real shame that this earthwork isn't around anymore, it would have definitely been a source of pride in this God forsaken community. Also, it could have been advertised as a tourist attraction, bringing in extra money into city. Not to mention that it is quite an interesting subject...