The Mourne Wall – commonly referred to by hillwalkers as “The Wall” – is a 31.4km (19.5 mile) long dry-stone structure marking the perimeter of Northern Ireland Water’s largest chunk of land in the Mourne Mountains, measuring approximately 36 sq. km (14 sq. miles). Writers occasionally compare it to the Great Wall of China, which is a bit of a stretch. Both are built of stone and pass over mountains, but that is where the similarities end.
Commissioned by Belfast City & District Water Commissioners (BC&DWC), the Wall was built by locals between the months of April and October over an 18-year period (1904 – 1922). Its primary purposes were to define BC&DWC’s property boundary and to keep livestock out of Silent Valley and Annalong Valley, thereby maintaining the standard of groundwater within the catchment area and minimising purification processes. That water would later be collected in two new reservoirs – Silent Valley (completed 1933) and Ben Crom (completed 1957) – to then be piped for consumption in the growing city of Belfast.
The Mourne Wall passes directly over ten proper summits (including six of the range’s fourteen mountains), and within 300 metres of three others (Slieve Commedagh, Slieve Bearnagh and Rocky Mountain). It also passes over four notable tops which do not qualify as proper summits due to having less than 30m prominence (Slieve Bearnagh East Tor, Slieve Corragh, Carn Mountain North Top and Moolieve). The Wall is roughly the height of an adult (you may not be able to see a passing walker on the other side), is just under a metre thick (please do not walk along its flat top – the Wall is very delicate), and includes three integrated stone shelters along its northernmost section.
Although a primary purpose was to keep livestock out of the rainfall catchment area, the Wall deviates on occasions from the actual ridgeline which defines the catchment boundary. These deviations occur along the following sections of the Wall: Wee Binnian to Moolieve; west side of Silent Valley Mountain Park to Slieve Muck; and where the Wall misses Rocky Mountain. It is unknown why these deviations occurred, but they are most likely to be the result of land purchase negotiations during the 1890s. Route 7* (Annalong Valley Horseshoe) and Route 13* (Silent Valley Horseshoe) refer to these deviations, but direct walkers instead along ridge sections where it would have been more logical to build the Wall.
One might wonder why the Wall-enclosed catchment area extends so far south in the Annalong Valley given that the Binnian Tunnel redirects water from the river 1.4km upstream from where the Wall crosses. This is because a reservoir was planned for Annalong Valley before the Wall’s construction even started. That idea was later abandoned due to difficulties encountered during the Silent Valley Reservoir project, by which time the entire Wall had long been completed. If the Binnian Tunnel had been part of the original masterplan, the Wall’s path across the Annalong Valley might be very different today.
The Mourne Wall has been a Listed Historical Building since 15th March 1996. In its listing details, the Wall is described as “the longest upstanding man-made structure in Ireland”. Regular maintenance is undertaken by local stonemasons commissioned by Northern Ireland Water.
* Route descriptions appear in Walking the Mourne Mountains.
Commissioned by Belfast City & District Water Commissioners (BC&DWC), the Wall was built by locals between the months of April and October over an 18-year period (1904 – 1922). Its primary purposes were to define BC&DWC’s property boundary and to keep livestock out of Silent Valley and Annalong Valley, thereby maintaining the standard of groundwater within the catchment area and minimising purification processes. That water would later be collected in two new reservoirs – Silent Valley (completed 1933) and Ben Crom (completed 1957) – to then be piped for consumption in the growing city of Belfast.
The Mourne Wall passes directly over ten proper summits (including six of the range’s fourteen mountains), and within 300 metres of three others (Slieve Commedagh, Slieve Bearnagh and Rocky Mountain). It also passes over four notable tops which do not qualify as proper summits due to having less than 30m prominence (Slieve Bearnagh East Tor, Slieve Corragh, Carn Mountain North Top and Moolieve). The Wall is roughly the height of an adult (you may not be able to see a passing walker on the other side), is just under a metre thick (please do not walk along its flat top – the Wall is very delicate), and includes three integrated stone shelters along its northernmost section.
Although a primary purpose was to keep livestock out of the rainfall catchment area, the Wall deviates on occasions from the actual ridgeline which defines the catchment boundary. These deviations occur along the following sections of the Wall: Wee Binnian to Moolieve; west side of Silent Valley Mountain Park to Slieve Muck; and where the Wall misses Rocky Mountain. It is unknown why these deviations occurred, but they are most likely to be the result of land purchase negotiations during the 1890s. Route 7* (Annalong Valley Horseshoe) and Route 13* (Silent Valley Horseshoe) refer to these deviations, but direct walkers instead along ridge sections where it would have been more logical to build the Wall.
One might wonder why the Wall-enclosed catchment area extends so far south in the Annalong Valley given that the Binnian Tunnel redirects water from the river 1.4km upstream from where the Wall crosses. This is because a reservoir was planned for Annalong Valley before the Wall’s construction even started. That idea was later abandoned due to difficulties encountered during the Silent Valley Reservoir project, by which time the entire Wall had long been completed. If the Binnian Tunnel had been part of the original masterplan, the Wall’s path across the Annalong Valley might be very different today.
The Mourne Wall has been a Listed Historical Building since 15th March 1996. In its listing details, the Wall is described as “the longest upstanding man-made structure in Ireland”. Regular maintenance is undertaken by local stonemasons commissioned by Northern Ireland Water.
* Route descriptions appear in Walking the Mourne Mountains.
Walking the Mourne Wall
As one of the most iconic human-built features in the Irish uplands, walking the Mourne Wall’s full length is a long-established and popular challenge among hillwalkers. Around most of its circuit, especially along the higher sections, conditions often permit walking on both sides of the Wall. Navigation along these sections is generally straightforward: just follow the Wall. However, things get significantly trickier along a couple of lower sections where the Wall cuts across Annalong Valley and Silent Valley.
As a result of these tricky sections, Mourne Wall Challenge walkers tend to deviate away from the Wall twice. The most popular version of the challenge is described in Route 25 of Walking the Mourne Mountains and is an updated version of the old challenge route which previously crossed Silent Valley via the lower dam wall. New paths in Silent Valley Mountain Park now permit a more southerly crossing of the valley. A couple of variations are also described in Route 25 for walkers wishing to maximise the length of Wall they walk.
Times
These are provided in Route 25 of Walking the Mourne Mountains.
Start/finish points
These are provided in Route 25 of Walking the Mourne Mountains.
Route descriptions
Depending on how much of the Wall’s length you want to include in your Mourne Wall walking adventure, three versions are described in Route 25 of Walking the Mourne Mountains and its two variations.
The Challenge Route: This version is the most popular route for walking the Mourne Wall. It includes 26.6km of the Wall’s 31.4km length, has no out-and-back sections, takes a shortcut across Silent Valley Mountain Park, and contains a diversion away from the Wall which includes 1.5km of road walking.
The Maximised Route: This version is for challenge hillwalkers wanting to maximise the length of Mourne Wall they walk without entering private land. It includes 29.4km of the Wall’s 31.4km length, has 2 out-and-back sections, takes a shortcut across Silent Valley Mountain Park, and contains a diversion away from the Wall which includes 90 metres of road walking. Described in Route 25 of Walking the Mourne Mountains and its Variation 1.
The Actual Route: This version is for the strictest of challenge hillwalking purists. It includes all 31.4km of the Wall’s length, has one out-and-back section (i.e. the access track start and finish), takes no shortcuts or diversions away from the Wall, and includes three short sections skirting the edge of privately-owned low-level agricultural land along the outer side the Wall. What would it take for this to become the official Mourne Wall Challenge route it deserves to be? Less than 4km of path development, no more than 10 new stiles/gates and some access arrangements. With a bit of luck, that may have already happened by the time you arrive to walk it. Described in Route 25 of Walking the Mourne Mountains and its Variation 2.
Fitness and safety
Given the length of the Wall and the amount of ascent/descent involved, a high level of fitness is required for single-day attempts. Two-day attempts with a night under canvas are popular among walkers looking for a more leisurely option. In the interest of safety, it is recommended that complete circuits of the Wall be undertaken during the summer months when daylight hours are longest.
Camping
There are no formal camping facilities along the course of the Wall. The closest campsite can be found at Meelmore Lodge which is roughly 3km off route near the halfway point. This can be accessed from three consecutive cols in the vicinity of Slieve Meelmore and Slieve Bearnagh, as identified in Route 25. If you depart from the Wall to camp at the end of day 1, you must return to that same departure point to continue the walk on day 2. Wild camping beside the Wall is a popular option for 2-day challengers. If you want to enjoy a sunrise/sunset from your tent, consider the northernmost chain of summits from Slieve Meelmore and Slieve Donard. Please leave no trace of your overnight stop. Always take a final look back when departing from your camping spot to make sure you leave nothing behind.
Water sources
There are no tap water supplies along the Wall. In Silent Valley Mountain Park, it may be possible to ask for a refill at the café. Given that much of the Wall follows ridgelines, there are very few flowing streams to serve as clean water sources on the route. Much of the H2O encountered along the ridgeline is likely to be standing water in isolated boggy areas (and probably rain). Some fast-flowing surface streams can be found by descending either side of ridges. The Wall crosses a stream on the south-east slopes of Slieve Muck, although the water quality is unknown. It would be worth carrying a water filtration system if you are trying to keep the weight down.
A freshwater pipe is located on the upper slope of Slieve Commedagh to the west of the stone shelter. This pipe is very easy to find close to the Wall on its south side and is conveniently positioned near the halfway point of Route 25 in Walking the Mourne Mountains. Another pipe is also present on the east slope of Slieve Meelmore on the south-west side of the Wall. This one is a bit further away from the Wall making it not so easy to spot.
How long is the Mourne Wall?
Answer: 31.4km (19.5 miles)
This figure has been determined from high-precision measurements taken from multiple printed and digital mapping sources and further checked using GPS tracking devices in the field. It is worth noting that many online sources mistakenly quote the Wall as being 22 miles long. This error is believed to have originated from misinterpreting the length of a Mourne Wall walking route described in an earlier guidebook which included a section of access track at the start and finish (as has also been done in Route 25 of Walking the Mourne Mountains). The incorrect figure appears to have stuck and continues to do the rounds online.
“The 22 mile conundrum”
In 2016, a survey was undertaken along the entire stretch of the Mourne Wall. One of the objectives of this survey was to solve what has been referred to as the “22 mile conundrum”. This involved surveying the full 19.5 miles of Mourne Wall and assessing the condition of nearby adjoining dry-stone walls to find the missing miles. With inadequate detailed records from the time of construction to refer to, and with a specified target of 22 miles to prove, the study comes across as a guesswork exercise.
The resulting report conveniently identified just enough candidate branch wall sections – including some which appear to pre-date the 19.5-mile Wall by several decades – to claim a total length which almost matches the study’s 22-mile target. Bearing in mind that the Wall was built to mark the water company’s property boundary and keep livestock out of the catchment area, the deliberate construction of unnecessary branch wall sections seems highly unlikely. Even if the course of the Wall had to readjusted due to property expansion during its 18-year construction, any redundant branch wall sections would have been demoted instantly and no longer considered part of the Mourne Wall.
If any of the Mourne Wall has "gone missing" over the years, the most logical place to "find" it is actually along both sides of the Dunnywater track leading from (and including) the walled entrance gates at Head Road to where the track crosses a known section of the Mourne Wall near the inlet well house beside Annalong River. The wall along the east side of this track is built to a standard similar to the Mourne Wall AND it encloses the Annalong Valley Superintendent's House, indicating that the track was in fact BC&DWC property at a time. A similar wall also follows part of the west side of the track. If this was the Mourne Wall, it would appear that a stretch of it has sadly been demolished. If Dunnywater track proves to be where 2.5 miles of the Mourne Wall went missing, any demolished section deserves to be fully restored.