St Michael's Mount is a small tidal island in Mount's Bay, Cornwall, England. The island is a civil parish and is linked to the town of Marazion by a man-made granite causeway, passable when the water is lower. The population of the parish in 2011 was 35. The castle and chapel have been the home of the St Aubyn family since about 1650, and is managed by the National Trust. The earliest buildings, on the summit, date from the 12th century.