Hannibal, Missouri
On a trip up north last year, I stopped overnight at Hannibal, Missouri, a famous place in its own right, but even more famous because of local resident Samuel Clemens writing as Mark Twain. It is a community steeped in history and has some great museums, downtown shops and interesting architecture. See photos below.
One of the tourist attractions in Hannibal is Mark Twain Cave, an amazing network of criss-crossing naturally-made underground tunnels near the Mississippi River. It was said to be the inspiration for the cave written about in The Adventures of Tom Sawyer.