Longhorn Cavern is in Longhorn Cavern State Park nine miles southwest of Burnet on State Park Road 4 in southwestern Burnet County. The area was once part of D. G. Sherrard's pasture, and the cavern was called Sherrard's Cave. When Backbone Ridge was formed several million years ago, water seepage formed holes in the underground limestone. By about a million years ago, these holes had become wide enough to form connecting rooms. The seepage became an underground river, and erosion and stalactite formation continued. The cave had several natural entrances. The number and kinds of bones found in it suggest that it was used as a refuge by predatory animals. In more recent history the cavern was used by Comanche Indians-hence the name "Indian Council Room" given to one of the chambers. The constant 65° F temperature and the layer of flint, useful for making tools, doubtless made the shelter very attractive. The Indians were driven out in the 1860s by the Confederate Army, which then used the cavern as a place to manufacture gunpowder. After the Civil War Indians again made use of the cave. Several outlaws, including Sam Bass, are thought to have sought shelter there as well. In the 1920s and early 1930s part of the cavern was used as a dance hall, night club, and restaurant. One of the rooms was used for theater presentations and religious services. In 1931 the state of Texas purchased the cavern and the surrounding ranchland for a state park. The Civilian Conservation Corps worked from 1934 to 1938 to clear the passages in the cave, to build levees for flood control, to dig drainage holes, and to install a lighting system. In 1932 the cavern and park were opened and operated as a concession by the Longhorn Cavern Company. Several private groups have had the concession during the years; in the 1990s the cavern and park were overseen by Longhorn Cavern, Incorporated. Eleven miles of the cavern has been explored, although the guided tour (offered several times daily, except Christmas Eve and Christmas Day) is only a 1¼-mile round trip.