CUMBERLAND CAVERNS, Tenn. (AP) — In decades of ceaseless touring, bluegrass icon Ralph Stanley thought he'd played in every venue imaginable.
Then he got an invite to play a "Bluegrass Underground" show earlier this year.
"It's a good day to be here," Stanley told a crowd of several hundred fans, some of whom hung from rocky ledges around the rim of the Volcano Room 333 feet below ground. "I hope we can get out. I've been playing for 65 years now, and I've never played in a cave."
In a few short years, "Bluegrass Underground" and the Volcano Room at Cumberland Caverns near McMinnville, Tenn., have become a hot destination for top bluegrassers and acoustic musicians around the country. And a new weekly show on PBS should help raise the profile of one of the nation's most unique concert spaces even more.
The show kicked off in September and acts like Ricky Skaggs, Darrell Scott, Justin Townes Earle, Mountain Heart, The Farewell Drifters and 18 South will appear in episodes this season. A second season's worth of shows will be taped early next year with a lineup that includes a few all-stars who are intrigued by the possibilities.
"I figure I've played everywhere above ground," Country Music Hall of Famer Vince Gill said. "We might as well go see what happens when you go underneath."
Todd Mayo had a similar sense of curiosity when he visited Cumberland Caverns for the first time as a tourist over Memorial Day Weekend in 2008.
Mayo had never visited a cave before and learned a handful of interesting facts on a tour with his family. Tennessee, for instance, is the nation's most cavernous state because of its limestone formations. And the cave, discovered in 1810, is the second largest in the U.S. east of the Mississippi, winding away under the hills of middle Tennessee for more than 32 miles.
His interest was really piqued, however, when they reached the Volcano Room, an unexpected cathedral-like space with a chandelier hanging from the ceiling about 40 feet above.
He immediately saw the possibilities.
"I asked the tour guide, 'Do y'all ever have live music down here?'" Mayo said. "And she said, 'No, but that would be a good idea.'"
Mayo ran with it.
His biggest concern was how the cave sounded and shortly had sound engineers take a look. Everyone was expecting it to sound like ... well, a cave. Turns out it was a pretty special cave.
"When they came down they were amazed," Mayo said. "I'm not a sound engineer but they said it basically has better acoustics than any manmade structure in the world, Carnegie Hall or wherever you want to say. It's literally akin to going to see a live concert in a recording studio."
That has been hard to believe for many of the performers scheduled to make the trip three stories down. Doyle Lawson, a two-time "Bluegrass Underground" performer, thought the sound might be a muddled mess.
Instead, he found the acoustics "excellent," he said. "I didn't know what to expect the first time we came here, but I found out the acoustics were just great. I was worried not so much for us — we use in-ear monitors so the separation would always be fine for us. What I was worried about was would the resonance be too much for the audience, too much bouncing around or whatever."
Turns out nature has been working out the kinks for a very long time.
"The Volcano Room has been formed by 3½ million years of water and time entwining," Mayo said. "There were two rivers running through the Volcano Room, one north-south, one east-west, and they created a whirlpool that through the ages carved out these wonderful porous, uneven spaces."
Just a few months after starting the process, Mayo put on his first show. He quickly lined up a radio deal, but had bigger things in mind. He hooked up with local producer Todd Jarrell, who has a history with PBS, and with the help of friends they built a show they hope will one day be as popular as PBS mainstays like "Austin City Limits" and "Soundstage."
Joining Gill in Season 2 will be The Del McCoury Band, The Civil Wars and Lawson with his band Quicksilver. So far, 60 PBS markets, including Boston, Dallas, Chicago and Seattle, have picked up the show, with about 60 percent showing it in primetime. And it continues to grow.
Even before the boost of TV exposure, however, the monthly show became a destination. Mayo has had several attendees from overseas and audiences often have a mix of locals and visitors. Mayo recently asked a couple where they were from. They responded California, but said they had heard about the show from friends in Michigan who'd already been.
"It's kind of a bucket list destination for folks," he said.