After Henry VIII divorced his wife, Catherine of Aragon, in 1533, England was threatened by attack fromFrance and Spain. To protect the southern coast Henry immediately set about building a series of forts which included Deal Castle, built in 1539.

Deal Castle has a very unusual shape, based on the theory that rounded walls would be better at deflecting missiles. It consists of six semi-circular bastions in the form of a tower with an outer wall of the same shape to protect it.  The walls had a series of gun observations so arranged that any attacker faced five tiers of canons.

The castle was never actually attacked from the seas during Henry's reign although it did become a Royalist stronghold during the Civil War and more recently saw German attack in World War II.

Inside the castle is an interesting display of other similar castles built during Henry VIII's reign on this  section of English coastline.