Lollapalooza is a sell-out.

For the first time since setting up in Grant Park in 2005, the music festival has sold out all advance tickets for its three-day run. What does this mean for folks attending the fest and Chicagoans in general?

People. Lots of people. Everywhere.

A crowd 270,000 deep is predicted to descend upon downtown this weekend for Lollapalooza’s 20th anniversary go-around, packing not only the festival grounds that eat up most of Grant Park, but also our urban arteries and conveniences.

Car, rail, bus and foot traffic will be heavily congested. Lakefront avenues will be shut down. Restaurant waits will be ridiculously long. Cab hailing will be an effort. And forget about booking a hotel anywhere in the city for the weekend.

Basically, Chicago will be a mess. A big, hot, sweaty congested mess.

Is it really worth it?

Yes.

Lollapalooza is a cash cow for both the festival organizers and the city. Tickets ranged in price from $60 to $215 a pop, and the hundreds of thousands of folks that forked over that mad dough will spend even more at area businesses.

Monetary pluses aside, though, this year’s festival is particularly strong where it really counts — the music.

Despite being a stellar showcase for young, up-and-coming artists, Lollapalooza in its current incarnation has always carried a strong nostalgic pull, featuring long-established acts or reunited groups who’ve dusted off their instruments once again to play at one of the country’s largest fest. This year’s line-up follows suit, but the must-see featured players pack a bigger punch.

Co-headliner Foo Fighters will forever be linked to Nirvana despite singer/guitarist Dave Grohl’s evolution from former Nirvana drummer into one of rock’s greatest frontmen. Their latest album, Wasting Light, is just as impressive as their self-titled debut and its classic follow-up, The Color and the Shape. Now a five-piece group with the addition of ex-Germs and Nirvana sideman Pat Smear, their performance promises power.

A Perfect Circle and Cee Lo share similar traits with Foo Fighters as acts that have reached beyond — and often eclipsed — past glories.

Dark, brooding and heavy, A Perfect Circle is an undeniable supergroup comprised of past, present and sometimes members of Tool, Smashing Pumpkins, Devo, The Vandals, Nine Inch Nails, Guns ’N’ Roses, Puscifer and more. And it’s an absolute joy to see no-holds-barred soul sensation Cee Lo, a former member of Atlanta hip-hop act The Goodie Mob, break into the mainstream. He’s done that musically with both Gnarls Barkley and as a solo act, and as a celebrity force popping up on TV singing with Muppets and on reality shows.

Lollapalooza 2011 does have its share of honest-to-God comebacks, of course, but this year’s standouts are more vital than previous rehashes of grunge and rap-metal acts best left dead.

The Cars, who perfectly melded power pop and New Wave in the '70s and '80s, reunite with lead singer Ric Ocasek back at the helm (let’s just forget that the Todd Rundgren-led band, The New Cars, ever happened. OK?). And the band that rose from the ashes of The Clash, Big Audio Dynamite, return to bring their incredibly unique mix of funk, punk, reggae and dance music to crowds 14 years since they disbanded.

The Canadian noise duo Death from Above 1979 even gets in on the act. Comprised of only a drummer and a bassist (who also does double duty on keys), the group broke up only five years ago after a brief stint in the stateside limelight, but they’re resaddling for Lollapalooza 2011.

DFA 1979 were loud, fast, melodic chaos during their heyday and being able to witness the maelstrom again is cause for celebration. However, this particular reunion raises questions about our collective sense of nostalgia.

Does the reunion of a band barely passed warrant the same lauds as the coming-together of a long-gone influential act? Is the return of DFA 1979 as important as The Cars’ comeback?

If the music retains its impact and ability to take one back to a particular place and time in the past, its history — or lack, thereof — is irrelevant. Nostalgia knows no age — a fact that will keep Lollapalooza going for another eleven years.

Other Chicago Journal recommended acts: Cults, Eminem, Ween, Lykke Li, Black Lips, Girl Talk, Joy Formidable, Dale Earnhardt Jr. Jr. PerryEtty vs. Carl Cox, Explosions in the Sky, The Mountain Goats, Deftones, Crystal Castles, The Kills, Damien “Jr. Gong” Marley & Nas, Beirut and Bright Eyes.