Photo Gallery: British Sea Forts 11/12/2010
 Three of the seven forts linked together in the Thames Estuary photographed on...
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Three of the seven forts linked together in the Thames Estuary photographed on Sept. 29, 1945. The towers were originally designed as first line invasion defenses and each was armed with a 3.5 artillery gun. The constructed forts were towed out to sea, sunk on sandbanks and then linked together by cat walks.