The Flakturm IV built by the Nazi Army all across the country were designed to be impenetrable concrete fortresses to shoot down allied bombers. The towers were feared by pilots during the war as they were terrifyingly efficient with elevators bringing ammunition from lower levels to upper levels and some even had built-in hospitals to care for injured soldiers.
Another purpose of the flak towers was to fulfil Hitler’s doctrine of might and power through architecture. These huge structures doubled as above-ground air raid shelters that would be a monument of German resolve after they won the war. As we all know, they didn’t win the war.
After the war, the allies tried to blow up these symbols of fascist power. The British tried to blow up one of the flak towers in Berlin with 25 tons of explosives to no avail. It was only on the third attempt and with 35 tons of carefully placed dynamite and a strategically weakened structure that it finally fell. Maybe that’s why they let the seven other flak towers stand.
The tower I visited in Hamburg is right next to a theme park and has now been converted into business space. Fancy having an office with few windows and walls that are 12-inches thick.