Castell Harlech is one of the great castles of north Wales: severe, compact, and spectacularly placed on a rock above the coast. Edward I began it in 1282 as part of his ring of fortresses meant to control Gwynedd, and its walls-within-walls plan is still easy to read from the modern entrance bridge.
The setting makes it. The castle once stood much closer to the sea, with a defended stairway down to a water gate so ships could resupply it during a siege. Today the sea has pulled back, leaving dunes and open land below, but the views from the towers are better for it: Eryri behind, Cardigan Bay ahead, and the town squeezed between rock and sand.