Turns out other major headliners joined them Saturday at the Washington Mall.
It was a day of music, politics and merchandise.
John Legend performed one the songs from "Wake Up!" his album of protest song covers with The Roots.
And Cat Stevens started to play his song "Peace Train," before being joined on stage by Ozzy Osbourne who sang his own "Crazy Train." Eventually, The O'Jays went on stage too to perform their own "Love Train." Musical puns! (Osbourne, by the way, performs at 1st Mariner Nov. 29.)
Kid Rock also performed a new ballad with Sheryl Crow, and was joined by future jailbird T.I. on video.
Below, video of Tony Bennett and the Ozzy Osbourne-Cat Stevens-O'Jays mashup. C-Span still has the entire 3-hour show online.
Cat Stevens, Ozzy Osbourne and the O'Jays' dueling trains:
And Tony Bennett performs "America the Beautiful:"
Photo: The Roots, Win McNamee/Getty Images