I was wondering when this would happen. Making music in the underground is absolutely nothing new. It has been going on for centuries, literally. Grand Cavern in Grottoes Virginia opened in 1804(the first cavern to open to public in the United States) and they held parties with live bands all through the 1800's. New Market's Endless Cavern did the same. Of course Luray Caverns houses the largest underground instrument in the world with the great stalactite pipe organ. Using the stalactites to create the music. The crystals in the formations will vibrate when struck and produce a tone and they hooked it up to an organ's keyboard. In Cumberland Cavern in Tennessee concerts are being held in a beautiful open chamber in the underground and here is a recording of one of those. Unfortunately the video does not do the sound You get justice. It is must to hear in person click here to find out how to do that.