GERMAN SUBMARINE BASE IN TRONDHEIM - The attack on Norway 1940 in colour. WW2

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Dora was built as one of two submarine bunkers in Trondheim, which was the main base for the 13th submarine flotilla. The submarine force in the north operated particularly in the Arctic Ocean against the allied convoys with supplies to the Soviet Union for unloading in the port of Murmansk to strengthen the allied efforts on the Eastern Front. However, they also operated elsewhere and as far south as the English Channel. Particularly famous is the story of U-480, the world's first submarine with stealth capabilities.
The facility Dora 1 had room for 7 submarines in five docks. Similar facilities were built in several places, including in La Pallice (close to La Rochelle) on the west coast of France for the submarines that operated further south in the Atlantic Ocean and west of the British Isles.
The plant must be seen in the context of Albert Speer's big plans for Neu-Drontheim near Øysand.
Five Serbian slave laborers were buried in concrete and died during the construction of the bunkers when a pile wall fell on them.
On 24 July 1943, the facility was bombed by American bombers. This was the only time Trondheim was bombed during the Second World War. Eight Norwegian civilians and 31 Germans died. A planned bombing raid by 171 British aircraft on 22 November 1944 was called off due to weather conditions and artificial fog.
Attempts were made to remove the bunkers after the war, but the roof is 3.5 meters thick with reinforced concrete and the walls are three metres, so it was not cost-effective to try to remove the facility. So much dynamite was needed that one would risk damage to the surrounding town if the plant were blown up.