SeaTheWorld

The Maunsell naval (sea) forts, built in the Thames estuary and operated by the Royal Navy, were to deter and report German air raids following the Thames as a landmark, and attempts to lay mines by aircraft in this important shipping channel.
(wiki link: https://en.wikipedia.org/wiki/Maunsell_Forts)

Note

If you all really like this fort, I’d be happy to make a full desk play set (there are a few versions of this building that have radio towers, cannons, look out decks, etc). Let me know :)

Pictures by Neil Brown (thanks!)
(http://www.flickr.com/photos/mrbeama)
Blog post with some amazing pictures
(http://desertedplaces.blogspot.com/2014/01/maunsell-forts-abandoned-sea-forts-from.html)