Greencastle Royal Castle

Built on a supreme location the impressive ditch surrounding the curtain wall was hewn out of the rock to a depth of nearly 12 ft and the stone used to build the curtain wall. A section has been excavated on this, the east side, and left open to view. You can see where a dam was built, though the ditch would hardly have held water because the rock is porous.

This royal castle, built in the mid-13th century by the Anglo Norman Hugh de Lacy to defend the southern approaches to the Earldom of Ulster. On a rocky height beside Carlingford Lough, it commanded the ferry link with Carlingford and defended sea and land communications, from Drogheda and Carlingford to Dundrum and Downpatrick. Clearly visible from the opposite shore is Carlingford Castle, probably also built by Hugh de Lacy. Greencastle was besieged and captured by Edward Bruce in 1316 and, despite being wrecked on many occasions, continued in use until the early-17th century.