Dora I

The capitulation of France two months later overshadowed the strategic importance of Norway to some extent, but it was still regarded as a better location for access to the Atlantic and Arctic Oceans than Germany.

[3] Construction of the bunker which would become part of the largest German naval base in Northern Europe, started in the autumn of 1941, one year after the invasion of Norway.

The work was undertaken by the Todt Organisation's (OT) Einsatzgruppe 'Wiking' and the Sager & Wörner construction company from Munich.

This incident fuelled a widespread rumor that the Germans simply left the bodies inside the wall.

Many Norwegian buildings were erected from timber so cement, sand and aggregate - components essential for the production of concrete - were often hard to extract in sufficient quantities.

Accumulated mud, on top of clay and sand layers proved to be incompatible with existing designs and was unstable ground so that the bunker had to be built in parts and stabilized before continuing construction.

[6][9] After the war, Dora I was to be blown up using dynamite, but this project was eventually cancelled due to the massive construction and the sheer size of the bunker.

[citation needed] The base was used by the Norwegian Defence Forces; two extra stories, painted in blue, were added.

[citation needed] Today, the former naval base is the home of the city and state archives, a bowling alley and several other businesses.

The submarine pens originally built for holding German U-boats are now being used as a harbour for civilian boats.