I thought this would be about the Luray Cavern’s Great Stalacpipe Organ.

“The Great Stalacpipe Organ is an electrically actuated lithophone located in Luray Caverns, Virginia, USA. Covering 3.5 acres of the cavern, it is considered the world's largest instrument by Guinness World Records.”

https://en.wikipedia.org/wiki/Great_Stalacpipe_Organ

A great place to visit btw