Forbidden Caverns in Sevierville, Tennessee, near the Smoky Mountains, combines striking geology with a long human history. Several hundred feet below the surface, it contains an underground river, grottos, chimney-like formations, a stream fed by a large underground lake beneath English Mountain, and a rare wall of cave onyx, while remaining about 58 degrees year-round. Its flint supplied Eastern Woodland Indians with material for arrowheads, knives, and scrapers. In the early twentieth century the caverns were used for moonshine production, then were planned for public development in the 1960s. After three years of planning and excavation, they opened in 1967 as a visitor destination.