https://www.axios.com/the-worlds-largest-instrument-exists-in-a-cave-2439864417.html?utm_medium=linkshare&utm_campaign=organic
Technically, Luray Cavern's Great Stalacpipe Organ is not an organ at all, but a percussion instrument known as a lithophone. Instead of blowing air through pipes, it operates by rhythmically striking 37 different stalactites scattered across the three-and-a-half-acre cave.