Named by Geoffrey of Monmouth as King Arthur's birthplace, Tintagel Castle occupies a headland on the rugged north coast of Cornwall. Excavations have revealed ruins dating to the 5th century AD when, after a period as a Roman settlemetn and military outpost it is thought to have been the stronghold of a Celtic king. The medieval castle that can still be seen was built by the Earl of Cornwall between 1233 and 1236.