Invented by the superbly named Leland W. Sprinkle in 1956 and situated in an underground cave in Virginia, the Great Stalacpipe Organ works by tapping on ancient stalactites with rubber mallets, all connected to a console that looks like a traditional organ. One of the popular stories surrounding the invention of the organ says that Sprinkle got the idea when his son hit his head on one of the stalactites, producing a low, vibrating hum from the cave.