The construction works were commenced late summer 1942, and completed so far that they could fire the main gun for the first time as early as in June–July 1943.
The fortress area is today the property of the Norwegian Armed Forces, while Stiftelsen Fjell festning are responsible for conducting the preservation and maintenance.
This was considered a time-consuming task, so the main entrance and gun emplacement were constructed as an open ditch, and later covered with concrete, instead of blasting a tunnel into and down in the solid rock.
It had three barrels, 28.3 centimetres each, and a range of 41 kilometres, from Fedje in the north to Stolmen in the south - but this was with the greatest possible charge.
Each barrel fired 3 shells at full charge, this caused an earth quake, shattered all windows in Fjell and flattened some barns.