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Ozzy Ozbourne at Lollapalooza in Chicago, Friday, August 3, 2012.
Lollapalooza is one of Chicago's biggest music fests, taking over downtown for three days to feature such headliners as Red Hot Chili Pepper, Black Sabbath, Frank Ocean and J. Cole. 270,000 people are expected to fill Grant Park this weekend.
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Fans at Lollapalooza in Chicago, August 3, 2012. This weekend 270,000 people are expected to flock to Grant Park for the sold-out music festival.
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Fans at Lollapalooza, in Chicago's Grant Park, August 3, 2012.
Lollapalooza is a party that's been taking place since 1991, and has made Chicago its home since 2005.
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Michael Angelakos of Passion Pit performs at Lollapalooza in Chicago, Friday, August 3, 2012.
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Fans at Lollapalooza, in Chicago's Grant Park, August 3, 2012.
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Michael Angelakos of Passion Pit performs at Lollapalooza in Chicago, Friday, August 3, 2012.
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Passion Pit bass player Jeff Apruzzese performs at Lollapalooza in Chicago, Friday, August 3, 2012.
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Michael Angelakos of Passion Pit performs at Lollapalooza in Chicago, Friday, August 3, 2012.
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Fans at Lollapalooza, in Chicago's Grant Park, August 3, 2012.
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Michael Angelakos of Passion Pit performs at Lollapalooza in Chicago, Friday, August 3, 2012.
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Fans at Lollapalooza, in Chicago's Grant Park, August 3, 2012.
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Passion Pit's lead guitarist Ian Hultquist performs at Lollapalooza in Chicago, Friday, August 3, 2012.
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Fans at Lollapalooza, in Chicago's Grant Park, August 3, 2012.
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Canoodling at Chicago's Grant Park during Lollapalooza, August 3, 2012.
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Fans at Lollapalooza, in Chicago's Grant Park, August 3, 2012.
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Dan Auerbach of the Black Keys performs at Lollapalooza, in Chicago, August 3, 2012.
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Drummer Patrick Carney of the Black Keys performs at Lollapalooza, in Chicago, August 3, 2012.
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The Black Keys perform at Lollapalooza, in Chicago, August 3, 2012.
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Dan Auerbach of the Black Keys performs at Lollapalooza, in Chicago, August 3, 2012.
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The Black Keys perform at Lollapalooza, in Chicago, August 3, 2012.
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Fans at Lollapalooza, in Chicago's Grant Park, August 3, 2012.
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Ozzy Ozbourne at Lollapalooza in Chicago, Friday, August 3, 2012.
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Black Sabbath performs at Lollapalooza in Chicago, August 3, 2012.
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Fans at Lollapalooza, in Chicago's Grant Park, August 3, 2012.
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Guitarist Tomy Iommi of Black Sabbath performs at Lollapalooza in Chicago, August 3, 2012.
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Bassist Geezer Butler of Black Sabbath performs at Lollapalooza in Chicago, August 3, 2012.
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Ozzy Ozbourne at Lollapalooza in Chicago, Friday, August 3, 2012.
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Fans at Lollapalooza, in Chicago's Grant Park, August 3, 2012.
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Ozzy Ozbourne at Lollapalooza in Chicago, Friday, August 3, 2012.
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Fans at Lollapalooza, in Chicago's Grant Park, August 3, 2012.
Photo by Theo Wargo/Getty Images
Fans are evacuated briefly from Grant Park due to an approaching storm, during 2012 Lollapalooza, Saturday, August 4, 2012 in Chicago.
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A girl dances in a mud puddle after thunderstorms forced the evacuation of the Lollapalooza festival in Chicago's Grant Park on Saturday, Aug. 4, 2012.
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Santigold (a.k.a. Santi White) performs at Lollapalooza in Chicago, Saturday August 4, 2012.
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Santigold (a.k.a. Santi White) performs at Lollapalooza in Chicago, Saturday August 4, 2012.
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Santigold (a.k.a. Santi White) performs at Lollapalooza in Chicago, Saturday August 4, 2012.
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Santigold (a.k.a. Santi White) performs at Lollapalooza in Chicago, Saturday August 4, 2012.
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Jane's Addiction performs at the Lollapalooza after-show, at the Aragon Ballroom in Chicago, August 4, 2012.
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Jane's Addiction front man Perry Farrell founded Lollapalooza.
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Perry Farrell of Jane's Addiction performs at the Lollapalooza after-show, at the Aragon Ballroom in Chicago, August 4, 2012.
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Lead guitarist Dave Navarro of Jane's Addiction performs at the Lollapalooza after-show, at the Aragon Ballroom in Chicago, August 4, 2012.
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Lead guitarist Dave Navarro of Jane's Addiction performs at the Lollapalooza after-show, at the Aragon Ballroom in Chicago, August 4, 2012.
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Jane's Addiction performs at the Lollapalooza after-show, at the Aragon Ballroom in Chicago, August 4, 2012.
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Jane's Addiction performs at the Lollapalooza after-show, at the Aragon Ballroom in Chicago, August 4, 2012.
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Jane's Addiction performs at the Lollapalooza after-show, at the Aragon Ballroom in Chicago, August 4, 2012.
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Perry Farrell of Jane's Addiction performs at the Lollapalooza after-show, at the Aragon Ballroom in Chicago, August 4, 2012.
