Longhorn Cavern State park is one of the most unique parks we have visited to date. There is no camping at this park, but Inks lake state park is just a few miles away if you need a place for the night. There is one main attraction here, the Cavern, and its awesome!  Thought to have been formed by an ancient underground river, the caverns have been around for centuries. The caves were used for shelter in prehistoric times, and was even mined for bat guano, to make gunpowder, during the civil war. The Civilian conservation corps cleared the caverns of debris in the 1930's, and built many of the structures at the park. there are two different guided tours available, that take you over 100ft under the surface into the cavern. you'll cover over a mile in distance over about 90 min on the tour. Children of all ages are allowed on the tour, just make sure they are ok with dim, and dark places. The caverns are rich with history, and legends, and the tour will not disappoint. Afterwards, you can rest up, and grab snacks and souvenirs from the gift shop.