England's Tintagel Castle is closely associated with the legend of King Arthur. It's situated on a small peninsula on the northern coast of Cornwall. The current structure was built in the 13th century. Tintagel was described extensively by the 12th century proto-historian Geoffrey of Monmouth, whose History of the Kings of Britain is credited with establishing the King Arthur legend. Tintagel had fallen into a ruined state and was "discovered" during an upsurge of interest in King Arthur in the mid-1800's.