Carlingford Castle, more commonly known as King John's Castle, lies in the town of Carlingford, in County Louth, in Ireland.
Carlingford Castle stands on a rocky outcrop by the shore, overlooking the harbour. It was built in the late 12th century by the Norman knight Hugh de Lacy. It was the first fortified stone structure in Carlingford. The castles of Carlingford and Green Castle, on the other side of the mouth of Carlingford Lough, at the foot of the Mourne Mountains, enabled the Normans to control the entrance to the lough. Its common name of King John's Castle is derived from the supposed fact that King John stayed here for 3 days in 1210.
The castle itself is a D-shaped enclosure castle. The curtain wall at the western side had a rectangular gate house and a square flanking tower and the south west. Portions of the northern tower of this gate house still remain. The curtain wall is well provided with deep embrasures with narrow defensive slits. During the second half of the 13th century a large rectangular hall was added on the eastern side. This hall had two main floors over a basement which is now largely filled with masonry with the great hall sited on the first floor of the castle overlooking the harbour.
Carlingford castle changed hands several times over the following centuries. Probably taken by Sir Henry Tichbourne in 1642, it was compelled to surrender to Lord Inchiquin in 1649. However in the following year it was delivered to Sir Charles Coote.
In 1689 it was fired upon by retreating Jacobite forces and later used as a hospital by General Schomberg during the period leading up to the Battle of the Boyne.
During the 19th century the Dundalk, Newry & Greenore Railway constructed a deep cutting on the landward side thereby enhancing the prominent position of the castle.
At present Carlingford Castle is not used for anything. Its interior can not be visited due to the danger from falling masonry, which is too bad because it seems very interesting, but you can walk around it freely. The town of Carlingford is a little bit touristy and there are two more castles in town; Taaffe's Castle and The Mint (another 16th century tower house which I didn't visit).