The War Memorial
In the center of the main park downtown there is a small memorial which features eight plaques dedicated to the men of Marion County who lost their lives in WWI & WWII. The sheer number of names was quite shocking to me, personally. There are literally hundreds.
Mark Twain's Hannibal
Some great names are associated with Hannibal, Missouri - Samuel Clemens (better known as Mark Twain), (The Unsinkable) Molly Brown, Tom Sawyer, Huckleberry Finn, Becky, Indian Joe - and their memories make this Mississippi River town an enjoyable place to visit.
Anybody who has read "The Adventures of Tom Sawyer" or "Huckleberry Finn" will enjoy a walking tour of downtown Hannibal, or riding a paddle-wheel steamer on the Missippi. These adventures and more are available here.