My second tip is to make your first stop Fort Ancient Earthworks & Nature Preserve. The excellent museum there will give you a great overview of American Indian history in Ohio and will inform your visits to the other sites.
My third tip is to schedule your visit to these sites when they are offering a guided tour. The knowledgeable staff members at each of these sites really bring the history to life and can answer your questions.
And my final tip is to talk to the staff at each of these sites. They’re so knowledgeable about their sites and can make recommendations that will make your visit truly special. Seriously—talk to them. They love it and you will too.
How much time: If you want to fully experience Fort Ancient, I would budget 3-4 hours. That’ll give you time to explore the museum, take one of their excellent tours, visit the North Overlook, hike a trail or two and make a purchase in the gift shop. Because I was on a very tight schedule, I did a quick perusal of the museum, drove to the North Overlook for the gorgeous view, saw a deer (!) and then headed to Chillicothe. Don’t do what I did—you’re missing out on too much.