Old Stone Fort in Coffee County, Tennessee, is a prehistoric Native American enclosure on a peninsula where the Duck and Little Duck rivers meet. Covering about 50 acres, it is widely considered the South’s most complex hilltop enclosure. Built gradually during the Middle Woodland period, likely between 80 and 550 AD, it was probably ceremonial rather than defensive, with low stone walls, no palisade, and little evidence of occupation inside. Its builders were identified as Native peoples of the local McFarland and Owl Hollow cultures. Preserved as Old Stone Fort State Archaeological Park, it remains a major archaeological site and historic landmark.