07/22/2011 05:08 pm ET Updated Sep 21, 2011

Lollapalooza 2011 Sells Out: 270,000 Fans Expected

If you're heading to Lollapalooza in Chicago this year, be ready for the usual heat and some massive crowds. The festival, which has been exclusively in Grant Park since 2005, sold out Friday--meaning 270,000 fans will attend the music fest August 5 through 7.

The Chicago Sun-Times explains just how popular the festival has become in recent years:

In 2005, the event's first year on Chicago's lakefront, daily attendance was 65,000.

The total daily capacity allowed for the festival, however, is 95,000. C3 said today that with VIPs and complimentary tickets on top of the 90,000, that capacity has been reached -- so no chance of extra tickets going on sale late.

While not the first festival when it launched July 18, 1991, in Phoenix, Lollapalooza was the ambitious archetype for the modern mega-festivals that have popped up since – Bonnaroo, Coachella and a legion of smaller multi-day parties. Most festivals previously had focused on one type of music or fan. But Perry Farrell spread the umbrella wide, opening the gates for bands whose touring presence was often the small club. But working together, those bands could command the stage with thousands looking on.

Farrell will celebrate the 20th anniversary of Lollapalooza with an eclectic lineup this summer in Chicago that knows no boundaries, from rock and rap and even pop, to dance music and experimental sounds that can't be described in a few words.

Though it's definitely not the Lollapalooza Farrell founded in 1991, he loves what it has become.

"I want to take care of my people," Farrell said. "They've been with me for 20 years. That's how I go. It's a family-run business at this point."

Some of the top names in music are among the Aug. 5-7 festival headliners announced Tuesday, including Eminem, Foo Fighters, Coldplay, Muse, My Morning Jacket, Deadmau5 and Cee Lo Green.

Check out some of Lolla 2011's biggest acts here. Check out the full lineup here.

Lollapalooza 2011 Lineup
Lollapalooza 2011 Lineup