Bluegrass Underground is a musical adventure series that shines a light on purveyors of musical authenticity in a space unlike any other on (or under) earth. Bluegrass Underground emanates from the Volcano Room, a subterranean amphitheatre 333 feet below McMinnville, Tennessee at Cumberland Caverns. The acoustic properties of the Volcano Room are singular. In fact the room only resonates at 2 frequencies meaning that experiencing live music there is akin to attending a concert inside a recording studio. Check PBS listing for full episode air times.