Great Seal State Park protects the rugged hills east of Chillicothe, the same landscape that inspired the hills shown on Ohio's state seal. It is best used as an active stop: the trail network runs for more than 20 miles, with routes for hiking, mountain biking, and horseback riding through forested ridges and valleys.
It is less polished than the area's Hopewell sites, but it gives you a good sense of the Scioto Valley countryside if you want a few hours outdoors.