Fort Hill State Memorial preserves a Native American earthwork built by the Hopewell culture about 2,000 years ago on a high, level summit above Ohio Brush Creek and the Ohio River. Though called a fort, it is a large walled enclosure of earth rather than a military stronghold, and archaeologists generally believe it had a religious purpose. The enclosure extends 8,619 feet, more than 1 1/2 miles around, enclosing 35.3 acres, with walls 6 to 15 feet high and 39 openings. The site gained early archaeological importance through excavations in 1846 and publication in 1848, and it is also recognized for notable geological features and natural history.