After we visited the giant ketchup bottle and took a picture of an interesting building that appeared to be part church, part BBQ place, we happened upon the Cahokia Mounds. We climbed Monk's Mound, and from the top, we could see several other mounds nearby. Next to them was Woodhenge, a circle of 40 tall wooden poles that were an ancient calendar.
It was starting to get dark, so we found a hotel with a barbecue place next door. In the morning we're planning to find a big shoe made of shoes and a cowboy muffler man, among other things.