There's loads of online articles on the Ohio mounds, including on FR. Not sure if it's on FR, but there are such mounds around these parts as well -- Indian Mounds park is right on the Grand River, and some simulated mounds (as a sort of nod-to) were built right by the public museum and the Gerald Ford museum.
Here's one idea. :')
cahokia site:freerepublic.com Google