Organ Cave in West Virginia gets its name from the Rock Organ, its largest formation, which resembles a huge church organ.

The cave is big enough to house many people. Organ Cave was once used as shelter for General Robert E. Lee troops during the American Civil War. On another occasion religious services for more than 1,000 men were given in the cavern.

Organ Cave was a major saltpeter-source for the production of gunpowder. The remains of this mining can be seen on the tour.

Organ Cave contains numerous troglobitic species. It is the perfect locale bats, and is home to 4 species of bats. Additionally paleontologists have found many fossils here, including Black Bear, Bobcat, Dire Wolf, Armadillo, Porcupine, Brown (Grizzly) Bear, Saber-toothed Cat, Complicated-toothed Horse, Long-nosed Peccary, Caribou and the tooth of an American Mastodon.