Surprisingly, Cincinnati does a very good job educating locals and visitors about their history, and the Freedom Center is a "must see" for people curious about area history. Due to its location on the Ohio River right across from a slave holding state, Cincinnati served as a major hub for the Underground Railroad.
The museum chronicles this history along with other threads associated with slavery and freedom. Although many exhibits are rather jumbled, it's definitely worth checking out. I didn't spend a great deal of time here, but I still learned a few new facts and found their "modern slavery" presentations thought provoking.
Note: If you have children, prepare to browse quickly and find a few highlights. There isn't much in the way of inter-active displays (outside a few "puzzle" like items that pose questions and you flip a piece to reveal the answer).