Peel Castle (Cashtal Purt-ny-Hinshey in Manx Gaelic) is a castle in Peel on the Isle of Man, originally constructed by Vikings. The castle stands on St Patrick's Isle which is connected to the town by a causeway. It is now owned by Manx National Heritage and is open to visitors during the summer.The castle was built in the 11th century by the Vikings, under the rule of King Magnus Barefoot.