Jeffers Mound is a Hopewell Indian structure, and is all that remains of a larger complex of earthworks. The original structure included a square enclosure covering approximately 8 acres, with the 20-foot high Jeffers Mound in the middle of the southern wall. A smaller mound was centered in the enclosure.
More information, with photo & diagram:
www.worthington.org/about/nregister/Jeffersfs.htm