For Lollapalooza, the saying goes "after the party is the after-party." With more than 50 after-party shows at 22 Chicago venues throughout the weekend, it seems the party never ends.

For fans not lucky enough to snag tickets to the festival, after-parties are an experience that provide fans special — and sometimes secret — indoor sets from major and emerging artists alike. Indeed, a big portion of the fans attending these shows at venues around Chicago aren't attending Lollapalooza, instead opting to pick and choose from a menu of more intimate after-shows.

Sometimes, performing at an after-party doesn't necessarily mean you're playing the actual festival. Only days prior to their actual show, the Foo Fighters announced a surprise Aug. 4 show at the 1,100-capacity Metro. The band performed for an unprecedented three-and-a-half hours to screaming fans. "Tonight we're going to try and break our record for the longest show ever," joked Dave Grohl onstage. Even after the concert began, a line of patient fans stood outside just to try to catch a glimpse of the GRAMMY-winning band and hear the songs from outside the venue.

Foster The People held court with a DJ set at a special after-party at Headquarters Beercade, a bar with arcade games. The band also played a second after-show, performing at The Vic to a sold-out audience, playing songs off their latest album Sacred Hearts Club.

Foster The People On "Using Joy As A Weapon" On Sacred Hearts Club

Ahead of his short 20-minute Lollapalooza set on Thursday, Liam Gallagher played a full-band set at Park West to a rowdy and enthused crowd, with some lining up as early as 5 a.m. The hour-long after-party set was ripe with solo favorites as well as Oasis hits, including "Be Here Now" and "Morning Glory."  His opening act was none other than U.K. indie pop band Blossoms, fresh off their Lollapalooza debut.

Besides the headliners, notable newcomers are liable to take various after-party stages. Case in point: Singer/songwriter Mondo Cozmo, who performed with fellow newcomer Billy Raffou, at Schubas Tavern to a packed house and vibrant audience. This was the first time Mondo Cozmo — Josh Ostrander —played his entire debut album in full. Canadian singer/songwriter Raffoul performed his singles "Dark Four Door" and "Driver," garnering an exuberant fan reaction.

Frenship — comprising James Sunderland and Brett Hite — kicked off Tegan And Sara's Aug. 3 show at Park West to a filled room. Frenship was able to whip the crowd into such a frenzy that by the end of the set people chanted, "More!" Following their after-party performance, the indie pop duo is set to continue work on their full-length debut album, with some songs being tested during their after-party performance set.

Whether it's your first Lollapalooza or you're a repeat attendee, an after-party show can surely be as fun as the main event. And while some shows, like the Foo Fighters' marathon set at Metro, can run into the wee hours of the morning, they can make your Lollapalooza memories all the more epic.

More Lollapalooza: Atlas Genius Talk Touring, "63 Days" Single

(Photo: Frenship perform at Park West on Aug. 3; Photo: Jacklyn Krol/The Recording Academy)