Battle of Pilot Knob State Historic Site is at jct. SRs 21 and 221. A Union post on this site was defended by 1,450 men under Brig. Gen. Thomas Ewing Jr. when it was attacked Sept. 26-27, 1864, by Maj. Gen. Sterling Price and 12,000 Confederate troops. The siege on the earthen fort cost Price more than 1,000 men and ended his march on St. Louis.
A visitor center features exhibits, a video presentation and a diorama of the Battle of Pilot Knob. Only an earthwork remains of the fort.