Stadion An der Alten Försterei (; ) is a football stadium in Köpenick and the largest single-purpose football stadium in the German capital of Berlin. It has been home to football club 1. FC Union Berlin and its forerunners since its opening in 1920. The stadium's capacity was last redeveloped in 2009 and expanded in 2013. Some of the redevelopment work was carried out by over 2,300 Union Berlin supporters volunteering their services. During league matches the arena features a total capacity of 22,012. There are 3,617 seats available whilst the rest of the ground remains terracing. The stadium became also known for events like the annual "Weihnachtssingen" (Christmas Carols Event) and the "WM-Wohnzimmer" (World Cup Living Room) in 2014. History 1920–1966 SC Union Oberschöneweide (forerunner of today's 1. FC Union Berlin) had to find a new home ground in 1920, as its former pitch had been built over by developers with residential buildings. The club moved a little further away from the city to the north-western part of the borough of Köpenick. The new stadium was officially opened in August 1920 with a match between Oberschöneweide and the then German champions 1. FC Nürnberg (1–2). The inaugural match at the Alte Försterei had already been played on 17 March, when Union challenged Viktoria 89 Berlin – an illustrious club who had won the German Championship three times around the turn of the century – to a friendly. Since 1966 When Union won promotion to the DDR-Oberliga (the top flight in East Germany) in 1966, the stadium soon needed to be expanded. The ground was first expanded in 1970 when the Gegengerade terrace was raised, whilst further extensions to the terracing at both ends in the late 1970s and early 1980s increased the capacity furthermore to 22,500. However, the somewhat spartan facilities at Alte Försterei had quickly begun to show their age though, as the club was not able to properly maintain the expansive ground as attendances – in common with the majority of clubs in the East and West – went into a serious decline. Later, after German reunification, when Union were assigned by the German Football Association to play in the 3rd league, the outdated stadium proved only one of a number of factors that hampered the club's push for promotion to higher leagues. Prior to the redevelopment in 2008, the terracing at the ground was in such