1. FC Union Berlin e.V., commonly known as Union Berlin, is a German professional football club based in the Köpenick district of Berlin. Founded under its current name on 20 January 1966, the club traces its sporting history to predecessor organisations established in 1906. Union Berlin has developed into one of the prominent football institutions in the German capital, with a strong supporter community and distinctive red-and-white identity. Its men's first team competes in the Bundesliga and plays its home matches at the Stadion An der Alten Försterei, located in Berlin-Köpenick. The stadium has a capacity of approximately 22,012 spectators. The club achieved promotion to the Bundesliga for the first time in 2019 and subsequently qualified for European competitions, including the UEFA Champions League for the 2023–24 season. Union Berlin also operates a professional women's football team, which earned promotion to the Frauen-Bundesliga for the 2025–26 season. Its wider sporting structure includes youth football and development programmes for boys and girls. The club focuses on developing young players through organised training, coaching and competitive opportunities. Union Berlin is particularly recognised for its close relationship with supporters, who have played an active role in the club's development and stadium history. The Stadion An der Alten Försterei was renovated with substantial volunteer involvement from supporters. The organisation also undertakes social and community activities, promoting inclusion, solidarity and opposition to discrimination. Its registered headquarters are located at An der Wuhlheide 263, 12555 Berlin, Germany. According to the club's official profile, it has more than 69,000 members, making it one of Berlin's largest sports associations. Through professional men's and women's football, youth development, supporter participation and community engagement, 1. FC Union Berlin maintains a distinctive position in German football.