Longhorn Cavern State Park

The limestone beneath Burnet County swallowed an underground river millions of years ago and left behind a cave that kept finding new uses. Native Americans sheltered here. Outlaws passed through — Sam Bass among them, though the stories around his visits have the quality of legend. In the late 1920s and early 1930s, area residents used the cavern as a nightclub, with shows broadcast via radio back to San Antonio. The CCC arrived in 1934, removed some 2.5 tons of silt and debris, and built stairs and walkways into the cave. It opened to the public in 1938 and was designated a National Natural Landmark in 1971. Entry to the park grounds is free; the cave itself requires a paid guided tour.