Construction of the Flakturm was completed by October 1943, absorbing 80,000 cubic meters of reinforced concrete—an attempt to blow up the colossus after World War II failed. From 2010 onwards, the Flakturm was repurposed as an 'Energy Bunker'. The Flakturm houses a biomass power plant and heat accumulator; solar panels cover the roof. On the top floor, a terrace gives you a view of Hamburg's port.