Bruce Springsteen, U2 Prep for Special Visit From Barack Obama at Inaugural Kickoff Concert (Rolling Stone)

Washington, DC — Under a pale and frigid sky, 50 gospel singers found themselves in the crosshairs of four American icons. To the south, the Washington Monument sliced the horizon above an iced-over Reflecting Pool. To the north, behind the stage they clapped and swayed on sat Abraham Lincoln, gazing out from the colonnaded memorial. To the east, a bald eagle named Challenger gripped his handler’s arm, awaiting his cue to soar. And to the west, stage right, there was Bruce.

On Sunday, Springsteen will join Beyoncé, James Taylor, U2, Mary J. Blige and more than half a million at the “We Are One” inaugural kickoff concert. Well, make that a half million and one — Rolling Stone has learned that Barak Obama will make the ultimate guest appearance, watching the show from an enclosure near the stage.

So as the mercury dropped, last-minute rehearsals went on Saturday, giving an early glimpse of a party fit for a president. As the choir raised their voices behind Bruce in the afternoon chill, Springsteen strummed and grimaced at flat notes of “The Rising.”

“Look, if you don’t know it, just move your lips,” he said impishly as the rehearsal got off to a shaky start. By the end, as tears streamed from some singers’ eyes — either from the extreme cold or the emotions of the moment — Springsteen was ecstatic. “You all sound so good,” he said. “I might as well not sing.”

For the past several days, the elite musicians and crews have braved sub-zero temperatures in preparation for the landmark concert. In a city of tents and trailers, unlikely bedfellows collaborated. The atmosphere at rehearsals was intimate and unhurried, the air pregnant with the excitement that not just music, but history was being made. Garth Brooks belted a medley of “American Pie” with a dozen local teenagers, telling them, “I’m going to embarrass myself — it’s how I learn.” Though James Taylor sported a nasty bruise around his eye, (whispers said he fell over his guitar case days earlier), he and John Legend crooned “Shower the People,” laughing when the house band snapped photos of him. “You know that part in Austin Powers, where he can’t stop looking at the guy’s mole?” he asked the musicians-cum-paparazzi, putting down his eggshell blue guitar. “I feel like that mole.”

Tucked under a rainbow cap, a wizened and frail Pete Seeger accompanied Springsteen with his banjo to run through a duet of “This Land is Your Land.” As the sun set, a familiar face in Washington stepped onto the stage. “I feel like I’m party crashing the American dream,” said Bono, shaking his head in awe and bowing to the cheering crew. In moments, the rest of U2 joined him, launching into “One” and “City of Blinding Lights,” pausing often to remark at the incredible moment in American history they were heralding.

Backstage, at the foot of the Lincoln Memorial there’s a sign that amusingly asks for “respectful silence.” Don’t count on it.