The Norman castle at Pevensey Bay is one of the most historic sites in Britain. It is built inside of a Roman wall, and was William the Conqueror’s headquarters. It was also used as a defense outpost by Brits and Americans in WWII It is currently several miles from the sea, but at the time when the Romans and Normans built the structures, the water lapped right up to the edge of the stone. The map below shows the bay 900 years ago, and the current seashore as a dashed line.