Perry Farrell's sonic extravaganza, now in its twelfth year, is underway in Chicago's expansive Grant Park. Nestled amid the city's skyscrapers and boasting a musically diverse lineup -- as evidenced by headliners Radiohead, Nine Inch Nails and Kanye West -- the three-day Lollapalooza event is sure to be a vibrant visual spectacle. So keep it here all weekend for pics of all the hot festival action.