Fort Jefferson park and monument marks the site of an advance outpost of General Arthur St. Clair, built in October 1791. It was named in honor of Thomas Jefferson, then Secretary of State. One of a chain of defensive forts built to protect army supplies from Indians, it served as a supply base throughout the campaigns of General St. Clair and General Anthony Wayne. It was abandoned in 1796.

The monument is made of faced granite field boulders, six feet square and twenty-feet tall. The area is maintained as a roadside park with a picnic shelter and grills. No part of the fort remains.