How Hamburg’s Flakturm IV was transformed from a Nazi bunker to a vibrant roof garden
Once an imposing Nazi-era bunker, Hamburg’s Flakturm IV has been reimagined with gardens, terraces and a soaring staircase. Designer Mathias Müller-Using’s vision turned a concrete relic into a vibrant civic landmark.
Even by bunker standards, the 35-metre-tall by 75-metre-wide concrete Flakturm IV in St Pauli was austere. Built using slave labour as both an anti-aircraft gun emplacement and an air-raid shelter in 1942, its symbolic weight could be said to exceed even its literal heft. But this behemoth’s postwar survival was less down to Vergangenheitsbewältigung (Germany’s efforts to face up to its past) than the lack of enough TNT to rupture its 3.5-metre-thick walls. So its looming ramparts continued to monopolise the Hamburg skyline. Designer Mathias Müller-Using could see the building from his living-room window. “Nobody had the courage to change it because it’s in the middle of the city and the Dom funfair happens beneath it three times a year,” he says. “No politician in Hamburg would touch it.”
But Müller-Using had a vision, inspired by Oscar Niemeyer’s Niterói Contemporary Art Museum, to weave a staircase around its ramparts so that people could access the roof. “I then thought: ‘It should be green and have life on it.’ The most important thing was making it a public space.”
Some 10 years later, in July 2024, his vision was realised – sort of. During the process of designing the bunker’s new terraced roof garden, which adds five new floors to the original structure, and its 560-metre winding staircase, Müller-Using fell out with the building’s owner and was once under a restraining order preventing him from entering this strange concrete ziggurat. But he can still see it from his office window and is proud of the part that he played in the creation of an architecturally inventive, highly popular and green public space.
