Marking its 100th year in existence, the 35km long Mourne wall in Co Down's Mourne mountains is to benefit from a multi-million euro restoration project.
More than 35kms long, the Mourne wall took 18 years to build, and was completed in 1922.
The wall crosses 15 of the Mourne mountains.
Repairs will be carried out on the granite structure by stonemasons, with more than €4.7m being invested by officials in Northern Ireland.
The stonemasons are using traditional methods of construction, and to date over 600 repairs have been completed.
A helicopter is averaging 100 lifts a day to bring stones to the required locations but workers have not been benefitting from the same luxury.
The stonemasons must make a daily hike of up to 6kms with their tools and supplies (including 1.82m planks), before they can start work.
Belfast Water Commissioners finished building the wall 100 years ago with the aim of marking and protecting the 9000-acre water catchment area, which feeds the Silent Valley and Ben Crom reservoirs.
The wall is 29.4km long and the circumference spreads right around that land.
There are extra walls inside the boundary, which mounts up to 35kms in total.
Mountain walkers find the wall a great aid to navigation and it is often referred to as "the handrail".
In decades past, walking the wall was a major attraction but due to concerns about erosion, visitors tend to be scarce today.
