Ynys Enlli
(Bardsey Island), Gwynedd
20,000 saints are reputedly buried on this small island and saints did, indeed, use it as a place of retreat from the beginning of the 6th century. Some say that Merlin is imprisoned here in a building made of glass. Other's say that the "Thirteen Treasures of Britain" are buried here. Could be Avalon where Merlin took Arthur on his final voyage!