The Maunsell Sea Forts were armed towers built in the United Kingdom in 1942. The Maunsell Sea Forts comprised naval forts that were designed with two cylindrical towers supporting a gun platform, like military grade bunkers, and army forts that were larger and interconnected by steel platforms. These forts were built in the Thames and Mersey estuaries, and used in World War-II to detect and deter German air raids.
Amazing Fact: While the army forts were in clusters closer to the shore, the naval forts were further out at sea.
