Tower, Slieve Donard (summit), Mourne Mountains, Newcastle, Co Down

This granite tower stands on the summit of Slieve Donard, the highest mountain in Northern Ireland, and was built in 1910 by the Belfast Water Commissioners. It is one of three similar towers located along the Mourne Wall, which defines the boundary of the catchment area for the Silent Valley reservoir; the others are on Meelmore and Commedagh.

The tower is a tapered structure, constructed with squared rubble granite facing outwards, brought to courses, and random rubble internally. The quoins have tooled edges, and the joints are strap pointed with cement. It measures 3.05 metres square at the base and rises 3.65 metres to the top of the oversailing coping, which originally consisted of finely dressed granite blocks. A thin layer of concrete now caps the tower, supporting a concrete Ordnance Survey triangulation post. The tower is situated against the Mourne Wall on its west and south sides. A narrow opening, 0.60 metres wide by 1.70 metres high, provides access to the internal chamber; its jambs are of coarsely dressed granite, and the lintel is finely dressed granite inscribed with the date '1910'. Cast-iron plaques reading "Belfast Water Works Trespassers Prosecuted" are fixed to the north and east elevations at the top of the tower.

The Mourne Wall itself was completed in 1922. Around 1950, the Ordnance Survey replaced the original coping and pyramidal cap with the current triangulation post, which involved removing the previous features. The tower serves as a shelter for mountain walkers and possesses industrial archaeological interest. Its group value relates to its connection with the Mourne Scheme and the Mourne Wall.