The Great Stalacpipe Organ in Virginia’s Luray Caverns is an electrically actuated lithophone that uses thirty-seven stalactites as sounding elements across about 3.5 acres of cave, making it the world’s largest instrument according to Guinness World Records. Its origins grew from a tradition, dating from the caverns’ discovery in 1878, of guides demonstrating musical tones from struck formations. Leland W. Sprinkle conceived and built the full instrument in the mid-1950s by tuning selected stalactites and connecting them to solenoid-driven rubber mallets controlled from an organ-style keyboard. Heard throughout the caverns, it became a signature attraction and a notable blend of geology and engineered music.