Deal is one of a series of castles built in the 1530s by Henry VIII as a defence against invasion from the continent. Unlike Norman castles with their keeps and high curtain walls, these all follow a different style: low-rise and with a distinctive clover-leaf shape. These rounded clover leaf walls protected against cannon balls, which were deflected, and also acted as gun platforms for defence. Their shape also meant all angles were covered and could provide a withering cross-fire. There was, and still is, only one entrance, well protected by a deep ditch and murder holes. Although the invasion of the 1530s did not materialise, further threats in later centuries meant that Deal was garrisoned almost constantly and never fell into ruin. Today it is managed by English Heritage. The whole of the castle can be visited, and about one hour should be allowed. It is open every day, 10am 6pm (5pm Saturdays), April to September. Refreshments are available. Access is possible for the disabled; the website has more detail.