Near Museumshafen Oevelgönne.
Entrance to vju, a café on the top of a bunker from WWII, or more specifically, a Flakturm – above-ground, anti-aircraft gun blockhouse tower. Eight flak towers were constructed by Nazi Germany in the cities of Berlin (3), Hamburg (2), and Vienna (3). See wiki for more.
Sorry, no wide lens at hand, but see a better photo here.
How to escape from bunker.
This building had something I found very familiar. It’s incredible how a hint of familiarity can instantly trigger so many feelings and memories.