Harlech   Harlech Castle Harlech Castle was built by Edward I in the late 13th century. Perched on rock, high above the coastal plain, it was ideally situated for keeping watch over land and sea. From the seaward side, the castles battlements are at the top of an almost vertical cliff face, while the landward side is dominated by an impressive twin-towered gate house. Between Harlech and the sea is an expanse of sand dunes. This illustrates the emergent coastline of Snowdonia, where deposition rather than erosion has shaped the coastal landscape.