"I think this is officially one of the greatest open-mike nights we've ever seen in Nashville," Urban said. "We're playing for the Hall tonight. We're the opening band for the real attractions."

In many ways, it was an unprecedented evening. Nine country stars took the big stage, with the show's second half evolving into a jam session in which Urban and Country Music Hall of Fame board president Vince Gill volleyed guitar riffs back and forth in service to songs from Taylor Swift, Faith Hill, Dierks Bentley, Jason Aldean, Lady Antebellum and Little Big Town. Proceeds from the event went to the Country Music Hall of Fame, and Museum Director Kyle Young said the night was " a landmark" and "easily the biggest fundraising event in the Hall's history."

And indeed, late in the evening Urban announced they're already planning to do it again next year. He said they had been inundated with requests from artists hoping to participate. "We easily could have filled two nights. Oct. 5 next year, we're going to do it all again."

"Just the exposure alone from a show like this ... how much is that worth?" Young asked.

Well, on Tuesday afternoon, the exposure brought twice as many tourists into the Hall of Fame than is usual on an October Tuesday. A thousand people paid the $20 admission charge, and many of them bought food and souvenirs.

"This was my hope," said Vince Gill, who conceived the "All For The Hall" campaign several years ago and who asked musicians at all levels -- stadium-fillers and honky-tonk scufflers alike -- to donate one night's pay to the Hall of Fame. "It was my hope, but I can't really believe it's happening. This is a big, big payday, and times are tough. But really, it makes so much sense to me to help out the place that documents all of this music that has happened and that happens now."

The show itself began with Urban and his band playing an hourlong set that featured hits including "Days Go By," "Who Wouldn't Wanna Be Me" and "Better Life." Urban also brought Brad Paisley on stage for a duet on "Start A Band" and played a plaintive version of Dolly Parton's "Coat Of Many Colors," in what the Australian-reared singer-songwriter called "an example of the music that influenced me to go to this country."

After a break, Gill emerged wearing a Nashville Predators jersey, flanked by a "house band" filled with A-list players including keyboardist John Hobbs, steel guitarist Paul Franklin and bass man Michael Rhodes. Gill, the band and Urban wound up accompanying six successive acts on two-song sets, climaxing with shrieks and lightbulb flashes for Taylor Swift's "Fifteen" and "Love Story."