Maunsell Forts: photos of abandoned English sea fort
The Maunsell Forts are located at the mouth of the Thames and were designed during the second World War to stop the Germans. These things are a hundred feet above sea level and are equipped with heavy and light guns. Since 2007, these forts are occasional used for broadcasts of Radio Red Sands.
read more: http://en.wikipedia.org/wiki/Maunsell_Forts