St Patrick's Isle 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 like Round Tower, St German 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 islet is now a tourist site within the castle walls. There is a public walk around the outside of the castle, which lines the coastal edge of the islet. The island's steep and rocky edges made it an ideal defensive outpost. It is said to be the place where St Patrick first set foot in the Isle of Man and was consequently named after him. It is connected to the City of Peel in the Isle of Man by a causeway over Fenella beach. In addition to the historic ruins, the island is partially a sealife sanctuary.