No Man's Land Fort
Nettlestone and Seaview, United Kingdom · built 1867
No Man's Land Fort, also referred to as No Man's Fort, is a sea fort in the Solent, near Portsmouth, England. It is one of the Palmerston Forts built between 1867 and 1880 after the recommendations of the 1859 Royal Commission. It is 200 ft (61 m) in diameter, and lies 1.4 miles (2.3 km, 1.2 nmi) off the coast of the Isle of Wight.
Fort data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).