The outer walls of the castle are Roman, built in the third
century AD, and enclose about ten acres. At that time the
castle was much closer to the sea than it is now. It was here
that, in September 1066, one Duke William of Normandy landed.
The following month he defeated Harold in the battle of Hastings.
The Conqueror conferred the Rape of Pevensey on his half-brother
Robert of Mortain, who began construction of a castle within
the Roman walls. Further fortifications were added at the
time of the Spanish Armada threat, and again during the Second
World War, with pill boxes disguised as ancient masonry.