One of the most extraordinary historical sites in southern England: a Norman castle built inside the walls of a Roman fortress. The Romans established Portus Adurni here in the late 3rd century as part of the Saxon Shore defences, and their complete circuit of walls still stands to nearly their full height — the most complete Roman fortifications north of the Alps. Inside, the Normans added a keep and a medieval royal residence. Two thousand years of continuous military history in one hilltop site, 10 km east of central Portsmouth.
Portchester Castle
Norman castle inside complete Roman fortress walls