The 20th annual Lollapalooza music festival held in Chicago ended day three with a downpour soaking attendees and a memorable performance by the Foo Fighters.

While weather held up for the first two days, the last day of the festival resembled a modern-day Woodstock, with Chicago's Grant Park turned into a massive mud slide as an estimated 90,000 concert goers were caked in filth from a heavy rainstorm.

Over 140 musical acts graced the 8 stages at the 20th anniversary of Lollapalooza, including Eminem, Coldplay, Muse, Cee Lo Green and Deadmau5, to name a few. Foo Fighters closed the show during a rainstorm playing tracks from their new album Wasting Light along with older hits.

Founded in 1991 by Perry Farrell, frontman of the alternative rock group Jane's Addiction, the sold-out Lollapalooza 2011 had a record number of attendees, estimated at 270,000. The event has since expanded to Chile and will launch its first show in Brazil next year, with more expansion in the future.

quotGirl Talkquot performs at the Lollapalooza music festival in Grant Park in Chicago
"Girl Talk" performs at the Lollapalooza music festival in Grant Park in Chicago August 5, 2011. The giant rock festival celebrating its 20th anniversary will run three days of music with 140 artists set to perform. REUTERS
A music fan crowd surfs during a performance by quotFoster the Peoplequot at the Lollapalooza music festival in Grant Park in Chicago
A music fan crowd surfs during a performance by "Foster the People" at the Lollapalooza music festival in Grant Park in Chicago, August 5, 2011. The giant rock festival celebrating its 20th anniversary will run three days of music with 140 artists set to perform. REUTERS
Matt Bellamy of the band quotMusequot performs at the Lollapalooza music festival in Grant Park in Chicago
Matt Bellamy of the band "Muse" performs at the Lollapalooza music festival in Grant Park in Chicago, August 5, 2011. The giant rock festival celebrating its 20th anniversary will run three days of music with 140 artists set to perform. REUTERS
Christopher Wolstenholme of the band quotMusequot performs at the Lollapalooza music festival in Grant Park in Chicago
Christopher Wolstenholme of the band "Muse" performs at the Lollapalooza music festival in Grant Park in Chicago, August 5, 2011. The giant rock festival celebrating its 20th anniversary will run three days of music with 140 artists set to perform. REUTERS
A general view shows the site of the Lollapalooza music festival in Grant Park in Chicago
A general view shows the site of the Lollapalooza music festival in Grant Park in Chicago August 5, 2011. The rock festival celebrating its 20th anniversary will run three days of music with 140 artists set to perform. REUTERS
Howerdel and Keenan of the band quotA Perfect Circlequot perform at the Lollapalooza music festival in Grant Park in Chicago
Billy Howerdel (R) and Maynard James Keenan of the band "A Perfect Circle" perform at the Lollapalooza music festival in Grant Park in Chicago August 5, 2011. The rock festival celebrating its 20th anniversary will run three days of music with 140 artists set to perform. REUTERS
Music fans make their way through the grounds at the Lollapalooza music festival in Grant Park in Chicago
Music fans make their way through the grounds at the Lollapalooza music festival in Grant Park in Chicago, August 5, 2011. The giant rock festival celebrating its 20th anniversary will run three days of music with 140 artists set to perform. REUTERS
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