St Patrick's Isle (Manx: Ellan Noo Perick) is a small island off the Isle of Man in the Irish Sea, largely occupied by Peel Castle and noted for its attractive and relatively well preserved historic castle ruins. These ruins include St Patrick's Church and an Irish-style round tower, St German's Cathedral, and the more recent residence of Lords of Mann. The ancient cathedral was left to decay in the 18th century, never to be rebuilt. The island's steep and rocky edges made it an ideal defensive outpost.