Abandoned Horse sands fort , Solent sea fortress Isle of wight . 

Horse Sand Fort is one of the larger Royal Commission sea forts in the Solent off Portsmouth, Hampshire, England. The fort is one of four built as part of the Palmerston Forts constructions. It is 200 feet (61 m) across. built between 1865 and 1880, with two floors and a basement and armour-plated all round.
An October 2018 report stated that restoration work on Horse Sands Fort was delayed "by the presence of a resident family of peregrine falcons".
In 2020, all three Clarenco-owned Forts were listed for sale. A news item stated that Horse Sand Fort was "a blank canvas, with 100 chambers and living quarters, plus the original gun carriage".
In October 2021, it was announced that the fort had been sold to an unnamed buyer for £715,000.