
Constructed in 1940-1941, apparently as a bomb-proof operations centre for the Admiralty, complete with gun emplacements, the Citadel has foundations 30 feet deep and a concrete roof 20 feet thick. It is known for its ugliness, described by Churchill as a "vast monstrosity which weighs upon the Horse Guards Parade", and its appearance has even been the subject of a debate in the House of Commons.
Sadly, it isn't open to the public as it is still used as a working building by the Ministry of Defence, but it is interesting to cast your eye over as you walk around the area. For more information click here.



