Hike to a natural bridge and sinkhole in the Ha Ha Tonka Karst Natural Area.
This park is best known for its castle ruins, which are also worth a visit. On the Colosseum Trail, you will hike down through a large 150ft deep sinkhole (the Colosseum) and under a natural stone bridge. After climbing out of the sinkhole you will reach a ridge with nice views. In spring, you will be in the company of blooming dogwoods and wildflowers.