Spitbank Fort is a sea fort located in the Solent, near Portsmouth, England. Work on constructing the fort started in 1861 and was completed in 1878. It is 162 feet in diameter across at its base, with 1 floor and a basement and armour plating only on the seaward side. By the time of completion the seaward side had received nine 12.5" thirty eight ton RML guns. In 1898 the role of the fort was changed to defend against light craft and the roof was fitted out with two 4.7" guns and searchlights. In the early 1900s all but three original large guns were removed, with minor upgrades to the smaller guns and searchlights continuing through the years. The fort was declared surplus to requirements in 1962 and disposed of by the Ministry of Defence in 1982. The fort is now privately owned, opens as a museum and has limited accommodation available.