Short on cash but with an abundance of devoted fans, club officials appealed for help when they were granted permission for construction work at their Alte Foersterei (Old Forestry) stadium.
Tucked away in the leafy southeast Berlin suburb of Koepenick, the stadium with its trademark old forest warden's office has been the home of the club since 1920.
Hundreds of fans volunteered after the call last June, offering their spare time, equipment, building material and experience. Fan commitment brought in close to five million euros' worth of work and resources.
"Our club, our stadium, our pitch, the Alte Foersterei," one volunteer worker wrote on the team blog on their website.
After years of legal wrangling, plus an escape from bankruptcy for the club, Union Berlin president Dirk Zingler announced 12 months ago that the team had finally been granted permission to refurbish the ground.
"The response from fans was stunning," said club spokesman Christian Arbeit. "Everyone started spending their holidays, their days off here. Others came on weekends, students worked during their semester breaks; absolutely stunning."
BLACK SHEEP
So far some 75,000 man hours have gone into the 20,500-capacity stadium, worth about two million euros. Sponsors supplied building material, equipment and manpower worth another 2.5 million euros.
From a few hundred, the band of helpers grew to more than 1,600 who worked in teams under six professional builders.
Daily, between 30 and 100 people continue to work on the stadium, with an online log charting their progress, as they prepare for the opening friendly against Bundesliga club Hertha Berlin on July 8, when all the volunteers will get in for free.
"The stadium becomes much more valuable this way. It carries more weight than one that was built by a big corporation," said Arbeit.
Union Berlin, third division champions this season, are used to doing things their way. For years they were the black sheep of East German soccer, with their fans under scrutiny by security services for dissent.
"This was always a club that had an alternative culture," Arbeit said. "It was not a club of resistance fighters but it was a club where people did not agree with everything in the GDR and they made their disagreement known."
Unlike hated East Berlin rivals Dynamo, the feared Stasi secret police team, the "Iron Union" attracted dissent.
"You came here if you had an alternative position, an alternative lifestyle. Nowadays it is all about opposing this commercialisation of sport," Arbeit told Reuters.
TEMPORARY HOME
That dissent was also visible during the Cold War when Stasi operatives meticulously logged details of fans at Union games.
During free kicks, as opposing teams lined u
