Starting today, thousands of people will flock to Manchester Farms, 60 miles outside of Nashville, Tenn., to experience four days of music. Starting today, June 11 through Sunday, June 14, hundreds of acts will storm nearly a dozen stages.

Traditionally known as a jam band festival, Bonnaroo has become more and more mainstream as the years have passed. In the following pages, HitFix correspondents pick 20 acts that can't be missed.

It's the Boss' only U.S. date this summer and, while Bonnaroo purists may quibble with whether he belongs at the jammy festival, why would anyone want to deny themselves of seeing one of the truly greatest live shows in rock? At 59, Springsteen isn't getting any younger, but you wouldn't know it when he does a backbend to start "10th Avenue Freeze Out" or hops on top of Roy Bittan's grand piano.