On July 13, 1985, music's biggest event since Woodstock took place. Live Aid was made up of two concerts held simultaneously at London's Wembley Stadium and John F. Kennedy Stadium in Philadelphia, and raised a reported $140 million for the efforts to aid famine victims in Ethiopia.

Live Aid was the next step after the success of two hit charity singles that had been released in the past eight months. The first, "Do They Know It's Christmas?," was credited to Band Aid, an all-star group featuring some of the U.K.'s biggest artists, such as Phil CollinsSting, Duran Duran, U2Paul Weller, Bananarama, George Michael and the Boomtown Rats, whose frontman, Bob Geldof, co-wrote the song with Midge Ure of Ultravox.

Less than two months after "Do They Know It's Christmas?" topped the charts around the globe came the U.S. version: "We Are the World" by USA for Africa. Written by Michael Jackson and Lionel Richie, the song collected an incredibly diverse group of musicians, including Bob DylanBruce SpringsteenRay CharlesCyndi LauperStevie WonderPaul SimonSteve PerryWillie Nelson and Dionne Warwick. Combined, the two charity tracks reportedly raised more than $75 million.

With work still not done, Geldof and Ure came up with the idea for Live Aid. The two concerts featured 24 hours of music (eight hours of which overlapped) and were attended by 172,000 people with a global TV audience estimated at two billion.

The London show started at noon with British rock heroes Status Quo singing John Fogerty's "Rockin' All Over the World," and concluded 10 hours later with Paul McCartney performing "Let It Be" followed by everybody singing "Do They Know It's Christmas?" Along the way, there were performances by Elvis Costello, Sting, U2, Howard Jones, Paul Young, Phil Collins and Dire Straits -- all of whom were riding high on the charts at the time. The Who even reunited for the event, although their four-song set was plagued by technical issues. And then there were Queen, who turned in one of the day's highlights.

In Philadelphia, the proceedings kicked off at 9AM ET, with folksinger Joan Baez singing "Amazing Grace" and telling the crowd, "This is your Woodstock." The U.S. lineup featured a more diverse group of artists than its U.K. counterpart, with R&B (Four Tops, Billy Ocean, Patti LaBelle), metal (Black Sabbath, Judas Priest), rap (Run-D.M.C.) and jazz (Pat Metheny sitting in with Santana) sharing the stage with rock and pop luminaries like the Pretenders, Tom Petty and the Heartbreakers, Madonna, Eric Clapton and the Beach Boys. It ended shortly after 11PM with an acoustic set by Bob Dylan, backed by Keith Richards and Ron Wood, followed by an all-star rendition of "We Are the World."

Philly was also the site of three reunions: Neil Young played with Crosby, Stills & Nash for the first time in a decade, and Ozzy Osbourne temporarily patched things up with Black Sabbath long enough to sing three songs. But the biggest reunion featured the three surviving members of Led Zeppelin onstage for the first time since the death of John Bonham. Phil Collins, as he did for Eric Clapton earlier in the day, occupied the drum seat.

Most artists were limited to 20-minute sets, but Collins worked even harder that day. After performing a two-song solo set ("Against All Odds" and "In the Air Tonight") in London, he boarded a Concorde and flew to Philly in time to sit in with Clapton, play the same two solo songs and then join Led Zeppelin onstage.

Another transcontinental moment took place when a video of Mick Jagger and David Bowie mugging their way through a cover of Martha & the Vandellas' "Dancing in the Street" was broadcast in both venues. It was released shortly after the shows as a single, and reached No. 7 in the U.S. and topped the U.K. chart.

Check out our individual stories about historic Live Aid sets from some of rock's biggest artists:

Black Sabbath
Phil Collins
Mick Jagger and Tina Turner
Led Zeppelin
Queen