And I'm willing to bet you know exactly what concert that was.

According to the Guinness World Records 2009, this particular show holds the world record, as 20 million requests for tickets were received online.

In the end, only around 20,000 people saw this historic event, a benefit held in memory of music executive Ahmet Ertegun.

And yes, it was headlined by Led Zeppelin, who performed their first full-length concert since the death of John Bonham in 1980 in their reunion at London's 02 Arena on December 10, 2007.

Last October, Celebration Day, the film from the historic event, was released to high praise.