Here with unique German military architecture from that era of the Second World War [WW2].
Above ground air raid shelters.
Protection from the combined strategic allied bombing offensive.
Concrete structures very sturdily built, robust in the extreme. A nearby bomb detonating probably leaving the occupants of the shelter unscathed. Thick walls and even roofs affording the maximum protection for the general populace, munitions factory workers and vital governmental personnel.
Air raid shelters strictly defensive in nature and not to be confused with the flak tower. The later having an offensive capability form the anti-aircraft-artillery mounted on the roof.
Thanks to a variety of web sites for the images.
A small sized air raid shelter but still affording protection to those gathered inside.
This air raid shelter resembles a missile about to take off. And is reputed to have a capacity of 500 persons. The base described as also being reinforced. Even a nearby hit the population inside relatively out of danger, even totally impervious.
This is a flak tower for comparison. A battery of anti-aircraft artillery [AAA] and searchlights mounted on the roof. That interior also serving as an air raid shelter. The persons lounging on the grass in the lower right hand corner give you some sense of the scale. These structures even seventy years later cost prohibitive to demolish?
This particular structure of multi-stories could very well accommodate 18,000 persons crammed in like the proverbial "sardine". Again, such a building so robustly build cost prohibitive to demolish?
When Albert Speer speaks of the allied [American and British] strategic bombing offensive during WW2 as causing great damage to the German war effort, he relates that a 1 million man army and impedimenta was needed to defend against the aerial onslaught.
That 1 million man army including in totality the day and night fighters, the fire fighting crews, the radar pickets and communication network, the air raid wardens, searchlight battery crews and AAA units, etc. Manpower again in totality and the resources as needed by same.
I might suggest resources and manpower to include the enormous quantities of concrete and those construction crews required to build these various bomb shelters.
I have also seen figures that the allied bombing offensive during WW2 resulted in one to two million German dead. This figure seems too HIGH to me. Devoted readers to the blog have a better "handle" on this? Let me hear from you.