This is the courthouse featured in many pictures that you see of the Arch. The courthouse was the scene of many rallies, speeches and several important trials, including the suit by Dred Scott for freedom from slavery and Suffragist Virginia Louisa Minor for the right to vote.
Galleries and exhibits show the history of the St. Louis area. Admission is free and they are open every day.
It won't take long and it doesn't cost you anything, so make a stop here while you are touring downtown. It's not a ton to see and the kids will probably be bored, but it is worth some of your time.