Beyond a water-filled moat, Beaumaris Castle is the last and most technically perfect of the "iron ring" of fortifications built by Edward I of England to consolidate his subjugation of Wales. Started in 1295, but never completed as fully designed, it enjoys World Heritage status. With its pleasing symmetry, water-filled moat, succession of four concentric "walls within walls" and stout towers and gatehouse, it was originally connected to the sea from the moat, allowing for efficient delivery of supplies.
The walk along the top of part of the inner wall gives super views of the castle layout. Look out for the old privvies (drop toilets, marginally less unpleasant than the murder holes for those walking below) and the arrow slits in the wall for picking off invaders. The inner ward is rather empty, since the planned lavish palace never came to pass, but you can check out the compact chapel in the Chapel Tower after a stroll through internal passages in the walls.
From a defensive perspective, the castle was hit-and-miss. It was captured by Welsh forces under the command of Owain Glyndŵr in 1403, but taken back in 1405. During the English Civil War, the castle was loyal to Charles I and held out against the Parliamentarian troops for four years.
