Not to be confused with Centerville, Ohio.Circleville is a city in and the county seat of Pickaway County, Ohio, United States, along the Scioto River. The population was 13,314 at the 2010 census.The city was originally laid out after 1810 within the 1100-foot diameter of a circle of a Hopewell tradition earthwork dating to the early centuries of the Common Era. The county courthouse was built in the center of the innermost circle.