From Ohio History Central
Fort Hill is one of the best-preserved examples in Ohio of a monumental hilltop enclosure. Prehistoric Native American people constructed it. A wall made of earth and stone winds around this prominent hilltop for more than one and a half miles. A ditch, or moat, inside the wall was one of the sources of the earth the builders used to make the wall. Measured from the bottom of the ditch to the top of the wall, the earthwork ranges from six to 15 feet in height and it encloses about 40 acres.
Although the site is known as "Fort" Hill, it probably never served as a defensive work. A "moat" on the outside of the walls would have been of more aid to the defenders. Also, there are more than 30 openings, or gateways, in the wall. So many entrances would have been difficult to defend.
Prufer found no artifacts in the Fort Hill wall trench or in any of the test pits he dug inside the enclosure. We still don't know exactly what the Hopewell builders of Fort Hill were doing on this hilltop nearly 2,000 years ago, but it was probably linked to the ceremonial activities they were performing down at the circular earthworks.