This Norman castle standing on a basalt promontory commanding the entrance to Belfast Lough and the port is the best preserved in Ireland. The heart of the building is its interior courtyard (1180-1200), surrounded by a high curtain. The seigneur's apartments were in the keep. A large model of the castle at the time of Schomberg's siege in 1689 illustrates the lives of the its inhabitants. St Nicholas' Church nearby is worth a visit to see its fine stone and alabaster monument, a homage to Arthur Chichester (1563-1625), governor of Carrickfergus.