Over 1,000 photos and 80 minutes of film material from the construction site have been preserved.
They were produced on behalf of the navy, which was resposible for building the bunker, and show the engineers' and designers' perspectives.
In particular, they document the technical processes of the individual work stages and the size of the construction site. The forced labourers only figure in them as part of the work process. Rarely do the photos reveal anything about their living or working conditions. The daily violence to which the forced labourers were subjected by their supervisors and guards is not shown.