The Upright Citizens Brigade has been the defining improv troupe of New York City since Amy Poehler, Matt Besser, Ian Roberts, and Matt Walsh first opened their theater in 1999, in the auditorium of a former burlesque theater in Chelsea. And though the institution is now associated with countless household names in comedy (Aubrey Plaza, Ellie Kemper, Donald Glover, and Adam McKay, to name just a few) the original "UCB4" are still practicing improvisors who reunite at least once a year for the Del Close Marathon.

This year, to celebrate its 20th anniversary, the original UCB are bringing their improv to one of New York's most legendary stages - Carnegie Hall. To kick off the Del Close Marathon (which runs nonstop Friday, June 29 through Sunday, July 1), the four will take the stage on Thursday, June 28 to perform their long-running ASSSSCAT improv revue, which features a monologist (typically a celebrity) followed by an entirely improvised long form show. Tickets are on sale now.

Now in its 20th year, the Del Close Marathon is 72-hour, non-stop improv marathon across multiple theaters in New York. It is a celebration of of Del Close, the controversial yet massively influential improv guru who essentially defined long form improv as we know it today through his book Truth in Comedy and his teachings. His students include founding SNL cast members, as well as the UCB4 and countless others. While the lineup for this year's festival has not been announced, every year the biggest alum from UCB come out to perform on insane improv lineups (Ben Schwartz and Horatio Sanz; Jon Daly and Jason Mantzoukas, the entire cast of 30 Rock) and create ridiculous midnight shows (Chris Gethard performs as Darryl Strawberry every year at his legendary 3 AM NY Mets Monoscene). Stay tuned for the full lineup.