Built after 1865, the Solent Forts Horse-Sands, No Man’s Land, St Helens and Spitbank forts were created to protect Portsmouth and it’s harbour from attack. The most likely culprit at this point would have been the french.
All of the forts are built from granite and are armour plated. Ranging in size from 150-200ft diameter and costing between £123,000 and £467,000 they were an expensive and impressive defensive against potential invaders. Luckily they never had to be used in warfare. The forts had to be armoured to prevent granite they were constructed from being smashed by cannon fire.
Two of the forts have recently been acquired and renovated in order to turn them into a luxury hotel and venue, meaning that the forts are going to be an active part of the maritime makeup of the solent in the near future.