Mourne Wall, Mourne Mountains, Co Down

The Mourne Wall is a substantial drystone wall traversing the Mourne Mountains in County Down. Constructed between 1904 and 1922 primarily by manual labour, it is unique as the longest upstanding man-made structure in Ireland and represents a significant example of a traditional Mournes drystone walling technique. Its construction is linked to the Mournes Scheme, which facilitated the transfer of water to Belfast. The wall serves as a recognizable landmark within the Mournes, often used as a guide for walkers navigating the area.

The section within this ward extends 8.1 kilometers (uncorrected for height) and runs from the north-west corner of the ward eastwards over Slieve Donard, south to just north of Rocky Mountain, along the ridge to Long Seefin, where it turns west, crossing the Annalong Valley to the slopes of Slieve Bignian. The wall is approximately 1.5 meters high and 80 to 90 centimeters thick, built from carefully placed roughly-squared granite rubble slabs hewn from local bedrock and boulders, without the use of mortar. The upper reaches of the wall are coped with transversely laid squared stones. Lower down, nearer the Annalong Valley, rounded fieldstones are more prevalent due to their increased availability, and the wall is generally lower, standing around 1.2 meters high. A substantial section west of the Carrick Little footpath was rebuilt using large rounded boulders extracted from drainage channels and laid by machine. Repairs to breaches in the wall have been made with matching stone.

The wall delineates the catchment area of the Belfast & District Water Commissioners’ Silent Valley Reservoir. It is of industrial archaeological interest and is considered to have group value.