The grandparents took some of our kids there this past summer as a stop along the way to go camping. Forgive the Vulcan sign, they had recently been to the Birthplace of James T. Kirk and somehow they got it in their head that you should always pose for shots with it.
The Adena Indian culture built the mound around 900 years ago. Trees had to be removed to really appreciate its size and artistry.
In order to preserve the mound, you can't climb on it, but there is an observation tower and a walking path that goes around it.
Park is open daylight hours (check the website for the specific month). Admission is by vehicle, $7 for a car if you don't have an Ohio State Park pass. Picnic tables and a small gift shop are available.
It's a little out of the way- south of Columbus and east of Cincinnati. The local town of Peebles is large enough for several fast food restaurants.
Similar Indian sites:
Angel Mounds, IN
Cahokia Mounds, IL
Mounds State Park, IN
Grave Creek Mound, WV
Alligator Mound, OH
Mound City, OH
Tell 'em we sent ya!