They came, they saw, they rocked. Neither rain, nor thunder, nor mud, nor malfunctioning gear could keep the Foos, the fans, the Mau5, the Monkeys or the Man from closing out Lollapalooza's 20th anniversary right.

Photos: Lollapalooza 2011 | Photos: Lollapalooza 2011 Portraits
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1. Just when we thought we'd seen the last rain on our parade, Mother Nature made us think again. The sky opened up just before 6 p.m., delaying Arctic Monkey's main stage set and turning the field into an inescapable mire of mud and filth. Everything was dampened... save the crowd's spirits. The party kicked back in as soon as the Monkeys fired up their amps, and Mudapalooza was born under a rainbow. Watch below.

2. "At least it's not us in the rain, at least it's just the f*cking Arctic Monkeys," Dave Grohl said were his thoughts earlier in the day, while perusing Weather.com. Ah, Karma. Thinking they dodged a bullet when the sky cleared after the Monkeys' set was delayed due to rain, Foo Fighters got an even worse dose of  the monsoon-like showers at the beginning of its headlining set over at the Music Unlimited stage. But the Foos, soaking wet and whipping their soggy locks, revelling in the wet experience as fans stayed put in the muck and were fully rocked, makeshift ponchos and all. "I'm glad it rained so f*cking crazy," Dave later added, seeming refreshed by the showers. As the band played through mostly hits and a handful of new songs off "Wasting Light," Grohl made his bias against electronic artists apparent, slamming those who do not use actual instruments, echoing the same sentiment he'd mentioned the night before, during the Foos' pre-Lolla warm-up gig at the Metro.

Lolla '11: Foo Fighters Go Full Throttle in Epic Club Show

3. Deadmau5 had the honor of being the only electronic act to play one of Lollapalooza's main stages. The man otherwise known as Joel Zimmerman seemed to hold nothing back as he bombarded the North end of the park with a spectacular display of beats, bass and blinding lights from his stage set. Things really got raving when SOFI bounced on stage to perform their hit "Sofi Needs a Ladder," which had every hand in the field reaching towards the skyline. But we can only guess how much more awesome it would have been if the rain hadn't effed up some of Deadmau5's gear during the set. "well, just walked off stage... er.. the pool that is," Deadmau5 posted to Facebook. "damn. at least some of the stuff worked up there on stage. Thanks Chicago! you rock... see you when I come back in oct.. this time without the rain and the tech issues. :)"

4. Last year, Lolla attendees got dressed up for Lady Gaga. This year: Deadmau5. Mau5-philes came prepared with giant mouse heads (like fan Nate Mann shown here stylin' in his blue head). And there were even whole families of fans who got into the act, like this shot of festivalgoer Chely and her brood in glowstick-mouse-ears and shirts.

5. Not to toot our own horn, but one of our favorite moments of Lollapalooza '11 was one that we orchestrated ourselves. Cover-couple Karmin stopped by our media tent to perform a stripped-down version of Dr. Dre and Eminem's "I Need a Doctor." After one take, we noticed that Skylar Grey, who sings the song's hook, happened to be wandering by. We made the introduction and the rest was gold. Watch below, as Skylar and Karmin rock the rap track on the fly.

6. How did the many photographers covering the event cope with the downpour? They hit the field and cowered UNDER the VIP platforms, looking like drowned rats under a pier.

7. As the early evening rain began to pour in sheets, Portugal. The Man knew just how to keep the crowd over at the Sony stage enticed. The psych-rockers ripped through a lean, mean cover of Oasis' "Don't Look Back in Anger," inspiring soggy singalongs.

8. In what had to be one of the fest's tenderest moments, a father and his pre-school-aged son shared the only umbrella'd table set up in front of the giant screen beaming out Foo Fighters' set in a farther field. While the rain came down in sheets, the guy and his little dude swayed along to "My Hero."

9. The Cars kicked off their afternoon set on the Music Unlimited stage by alternating tracks off their new album, "Move Like This," with '80s classics like "Just What I Needed" and "Let the Good Times Roll." The crowd, largely comprised of attendees who could remember the band was at its '80s peak, were not shy about which tracks they preferred, even through some minor tuning issues.

10. What happens when you're out on the street between the Foo Fighters' stage and the Deadmau5 stage right at the point where the two sounds blend into some bizzaro-world mashup? Well, one clearly sozzled and soggy fan decided to begin breakdancing. On the concrete. In the rain. Shirtless.

Lollapalooza 2011: 13 Things Seen & Heard Saturday

11. And while the real festival nostalgia moment -- fans frolicking in the mud -- evoked the music fest that began it all: Woodstock, Lollapalooza 2011 did it's little part to nod to this being its 20th anniversary. There was a little museum where you could go gawk at Wilco's Nudie suit from 2006 or take your picture with a giant blowup of Soundgarden and Pearl Jam backstage together in '92. Pete Wentz got a little lump in his throat telling us about checking out Snoop Dogg back in '97. And particularly on Sunday evening, as the sky dumped rain and made everything a little bit gauzy, the parade of younger people in brand new retro-styled 2011 Lollapalooza shirts mingled almost un-ironically with the sprinkling of people their parents age wearing the originals from 1991 and 1992.