Because the acoustics are not uniform throughout the cavern, it can be difficult to play by ear. So an automated system — using a plastic sheet with holes in it that rotates around a metal drum — plays songs similar to a player piano. When the metal meets the drum, corresponding stalactites sound off.

Go deeper: A combination of Mother Nature’s work, time and a skilled mathematician helped create the Great Stalacpipe Organ. The large, echoey chambers of Luray Caverns have formed naturally over the past 400 millions years. Calcium-rich water droplets eventually formed the large stalactites that hang from the cave’s ceiling and now act as an integral part of this instrument. Back in 1954, mathematician and electronics engineer Leland Sprinkle visited the caverns. As was customary during these tours, the guide would strike the stalactites to show visitors how each one gave off a unique sound. That moment sparked an idea in Sprinkle’s head — create the Great Stalacpipe Organ, which he did in three years.