Her Majesty's Royal Palace and Fortress The Tower of London more commonly known as Tower of London.
source: http://upload.wikimedia.org/wikipedia/commons/0/05/White_Tower_%28July-2003%29.jpg//


Some writers, such as Shakespeare in his play Richard III, have ascribed an earlier origin to the Tower of London and have stated that it was built by Julius Caesar. This supposed Roman origin is a myth, however, as is the story that the mortar used in its construction was tempered by the blood of beasts.

source: http://www.asht.info/assets/images/TL_Building_Large.jpg//


source: http://www.atpm.com/7.05/london/images/tower-of-london-420.jpg