University of Dayton Arena (commonly known as UD Arena) is a 13,435-seat multi-purpose arena in Dayton, Ohio. The arena opened in 1969. It is home to the University of Dayton Flyers basketball teams. Since 2001, it has been the birthplace of "March Madness." From 2001 to 2010, the facility hosted the annual "play-in" game in the NCAA men's basketball tournament (officially the "opening round" game) which featured the teams rated 64th and 65th in the tournament field. In 2011, when the tournament expanded to four opening round games, the arena continued to host all "first four" games.