This natural landmark is the second longest cave on the East Coast and it is also a history of the world and the people who lived here. Fossils of prehistoric animals were found here as well as Native American artifacts. The cave was also an important part of the Civil War, producing saltpeter for gunpowder. The name comes from the alien-like formation that resembles a huge pipe organ. You can see all these incredible marvels on the guided tours which are, according to the website, "based on the Book of Genesis..."