Starlight Castle is a folly on the grand Seaton Delaval estate close to the Northumberland coast. Today only a small section of wall survives, and historic photographs and postcards show it already in ruins a century ago. It was probably built by Sir Francis Delaval (1727-1771) in the middle of the 18th century. The story goes that Delaval wagered he could build a castle overnight, and this was the result.