The theme of Tuesday's All for the Hall benefit concert in Nashville was a celebration of country bands, duos and groups. But the Band Perry's Kimberly Perry perhaps summed up best what the night was truly all about: "To know where you're going, you've gotta know where you've been," she said.

The Band Perry was the youngest act to take the stage at the star-studded, sold-out event at downtown Music City's Bridgestone Arena. It was a night that celebrated hits currently on the charts, like the sibling trio's "Postcard From Paris," to songs that date all the way back to when their parents were young kids, as surprise guests Merle Haggard and Don Williams graced the stage to sing some of their classics.

The night's organizer, Keith Urban, kicked off the show with his infectious "You Gonna Fly" and "Sweet Thing." During the latter song, he introduced his "spiritual brother" and co-host for the night, Vince Gill. The two guitar slingers remained on stage throughout the concert, acting as the backing band for every artist.

The spotlight shone on Vince next and staying true to the night's theme, he dug way back into his catalog to before he was a solo artist and played the classic "Amie," a song he sang night after night back in the late '70s, when he was with Pure Prairie League. Vince also paid tribute to the Bakersfield Sound movement, singing the 1964 Buck Owens' hit, "Together Again."

Following Vince were Thompson Square, who sang "Are You Gonna Kiss Me or Not" and "I Got You," and then Blue Sky Riders. "We're Blue Sky Riders and you've never heard of us," joked the group's Kenny Loggins, who is joined by famed singer-songwriters Georgia Middleman and Gary Burr in the new trio. And though the audience may not have been familiar with the song they performed, "Dream," most everyone remained on their feet, giving them a warm welcome into the country music community.

The cheers became deafening when Pistol Annies -- Ashley Monroe, Angaleena Presley and Miranda Lambert -- took the stage. "Thanks to Vince and Keith for being our backup band -- that's hot!" said Miranda after her new trio performed their hit, "Hell on Heels." The three lovely ladies ended their set with the sassy "Takin' Pills," trading lead vocals on each verse.

Two more groups known for their delectable harmonies followed. Diamond Rio performed their huge hits "Unbelievable" and "Meet in the Middle," the latter song featuring a mean guitar solo by Vince Gill. Little Big Town was next, introduced by Keith as four of his best friends in the business. The quartet dazzled, as always, with a new song, "Front Porch Thing," followed by their breakthrough hit, "Boondocks."

The Oak Ridge Boys then took the stage, with the group's Joe Bonsall joking, "We're the oldest act here!" But they certainly had just as much -- if not more -- energy as any other act of the night. The legendary group danced around the stage and even jumped up and down as they sang the chart-toppers, "Elvira" and "Bobbie Sue."

Introduced by Vince as "the hottest group in the whole wide world," Lady Antebellum was up next, and returned the favor by singing "Happy Birthday" to Vince, who turns 55 tomorrow (April 12). The audience, from the floor seats all the way up to the nose bleeds, was on its feet as the trio sang "We Owned the Night" and "American Honey."

The 1978 CMA Male Vocalist of the Year and all-around American treasure, Don Williams, was the first surprise guest of the night. Keith and Vince provided beautiful harmonies for the legend on his classics "Imagine That" and "Tulsa Time."

The legendary Alabama continued their reunion gigs with a set that had the audience singing along, word for word. The group played "Feels So Right" and "Lady Down on Love." "There is nothing like the sound of those voices," said Keith after their performance.

Two of the hottest trios in today's country music followed, the Band Perry and Rascal Flatts. The sibling trio performed "Postcards From Paris" and "You Lie," with the Flatts next introducing the title track to their new album, "Changed," followed by the rousing Tom Cochrane classic that the country trio also made famous, "Life Is a Highway."

Rascal Flatts left the stage only to be called back by Vince, who also summoned fellow Grand Ole Opry members Diamond Rio and the Oaks back onstage. He explained that they all had a special present for their buddy, Keith Urban, who clearly had no idea what was going on as a heavy black duffel bag was dragged onstage. He unzipped it to find a WSM/Grand Ole Opry microphone stand, and Vince explained that the Opry would like Keith to become its newest member.

"I'm shocked!" said Keith, choking back tears. "What a huge honor and how beautiful to have this happen tonight!" The Australian crooner will be inducted during a special Opry ceremony on April 21. Watch a video of his Opry invitation here.

The final surprise of the night was the Okie From Muskogee himself, Merle Haggard. Wearing a black hat, blazer and a T-shirt emblazoned with the words, fittingly, "Life is good," the country legend was joined by Keith and Vince for what was the longest set of the night. He played "I Think I'll Just Stay Here and Drink," "Today I Started Loving You Again," "Working Man's Blues" and -- per Keith's request -- "Silver Wings."

Rock and roll's most legendary group was honored for the show's grand finale, as every act of the night joined Merle, Keith and Vince onstage for the Beatles' "I Saw Her Standing There."

All for the Hall is an annual concert that benefits Nashville's Country Music Hall of Fame and Museum. The money raised from Tuesday's incredible event will go toward a $75 million expansion of the tourist attraction.

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