Union South is a student activity center located on the University of Wisconsin-Madison Campus. It was established in 1971. The first building was demolished in 2009 and a new facility opened on April 15, 2011.^[1]

The building features lounges, an outdoor terrace and pavilion with a fireplace, a rock climbing wall (must be 18 or older to climb), a bowling alley, and billiards, along with several dining options. It also features several on-campus arts venues, including the university's chief film venue, The Marquee, as well as The Sett for music performances and Gallery 1308 for visual art.^[2] The building has 60 guest rooms, 17 meeting rooms, a video conference room, a 180-spot underground parking garage (two stories below ground), and Varsity Hall.

Varsity Hall is a 10,778 sq. ft. multipurpose event space on the second level of Union South.^[3] Varsity Hall features hardwood flooring as well as natural light from both the west and south. The hall opens onto a lounge that overlooks the Union's south plaza and Camp Randall. Varsity Hall Lounge has a baby grand piano and opens onto the second-floor Badger Deck.

Every game day, Union South is host to the Badger Bash, a pre-game and post-game tailgate during Wisconsin Badgers football games. The bash includes a performance by the UW Marching Band before the game.