Unique in design, and probably the most well-known structure on the Atlantic Wall. MP4 served the same purpose as the round naval range-finding towers on the Channel Islands. Built on five levels, each level was to have served one of the five naval gun batteries planned for the island. In the event only three naval batteries arrived, and the two other levels were given over to the army for their batteries. In the latter part of the war a 'Freya' radar was mounted on the roof.