Mumford & Sons + The Vaccines + Bear's Den

No one would have guessed back in 2008 that these posh, polite, bluegrass popsters would go on to play for Obama and shift a million copies of their second album—last year's Babel—in its first week of release. But their heartfelt, rousing, banjo-twangin' indie folk has struck a resonant chord with the masses, and they continue to delight fans in enormo-domes across the globe. Tonight's Brit extravaganza takes place at the recently renovated Forest Hills Stadium, and also features fuzzy U.K. pop crew the Vaccines.