Spitbank Fort Clarenco Hotel, Solent, Portsmouth, England

Work on constructing the fort started in 1861 but was soon halted for a review into the best way to defend the Solent and approaches to Portsmouth Harbour. Work restarted in 1867 and was completed in 1878.
Spitbank is smaller than the two main Solent forts, Horse Sand Fort and No Man's Land Fort. Its main purpose was as a further line of defence for ships that made it past the two main forts. It is 162 feet in diameter across at its base, with 1 floor and a basement and armour plating only on the seaward side. It was originally planned to have been armed with nine 10" eighteen ton rifled muzzle loader (RML) guns on the seaward side, and six 7" seven ton RML guns on the landward side. However, by the time of completion the plan had changed so that the seaward side received nine 12.5-inch muzzle-loading (RML) guns. From 1884 more modern 12-inch breechloading guns were installed and these were in service until after World War I.
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. Minor upgrades to the smaller guns and searchlights continued 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 and once opened as a museum. It has 50 rooms, its own dance hall, restaurant, and was once available for private functions with limited accommodation available. It was the venue for the Coalition Festival in the summer of 2009, and other psytrance and hard dance parties.