Approx 10 miles off the Harwich seafront, HM Rough Tower was the first of originally 4 naval forts designed by G.Maunsell to protect the estuaries and east coast.

The forts consisted of 2 re-enforced concrete towers, topped with a steel platform. The whole fort was constructed on a re-enforced concrete pontoon, which was floated into position and then sunk onto an unprepared seabed.