Narrow Water Keep is an Elizabethan tower house and bawn near Warrenpoint on the northern shore of Carlingford Lough. It was built in the 1560s to secure the centre of the Lough and to accommodate English soldiers guarding the narrowest point where the Clanrye River flows into it.
There has been a keep on this site since 1212. The original was built by Hugh de Lacy, the industrious first Earl of Ulster, as part of a frenetic castle-building programme to protect the Earldom of Ulster.
Rectangular and three storeys high, Narrow Water Castle is fairly typical of tower houses erected in Ireland between the fourteenth and early seventeenth centuries, although it is unusual in having straight stairs in its walls instead of spiral stairs.
The castle briefly fell into the hands of the Chief of the Mournes, Hugh Magennis towards the end of the sixteenth century, before being recaptured by the English. The castle was sold to the Hall family in 1670 and they held it for almost 300 years. For much of the eighteenth century a saltworks operated from within the enclosure.