Beaumaris Castle is the last and largest of the four UNESCO-listed castles Edward I built to subdue Wales after his 1282 conquest. The design is a perfect concentric plan — a lower outer wall with twelve towers ringing a higher inner ward of four massive towers and two great gatehouses — with a moat connected to the sea so that supply ships could once sail right up to the castle dock. The symmetry on paper has never been surpassed in Britain.
Walking the walls and climbing the towers takes an hour or so. The chapel tower, with its vaulted oratory, is the most complete medieval interior. From the outer walls there are wide views across the Menai Strait to the Snowdonia mountains, particularly fine at sunset. Run by Cadw, with an audio guide and small exhibition on Edwardian castle-building.