Overview
The British army built this road to catch one man. After the 1798 rebellion, rebels under Captain Michael Dwyer were using the Wicklow Mountains as cover, and there was no road running north to south across them. So the army cut one: 56 km of it, from Rathfarnham on the southern edge of Dublin over the high bog to Aghavannagh, with the spur most visitors drive today running down to Laragh and Glendalough. It worked as a military project and, two centuries later, it is one of the best mountain drives in Ireland – a free public road (signed R115 and R759) open around the clock.
If you only have an afternoon, drive it south from Rathfarnham to the Sally Gap, stop at the Lough Tay viewpoint, and carry on down past Glenmacnass to Laragh. That single run takes in the best of it. The full thing is two to three hours with stops, and pairs naturally with Glendalough for a day out.
One honest caveat before you set off: this is a drive that lives or dies on the weather. On a clear day the views run for miles; in low cloud or heavy rain you are paying narrow, exposed roads for the privilege of seeing nothing. Check the forecast, and if the tops are in fog, save it for another day.
History & Background
Construction began on 12 August 1800 and finished in October 1809, under engineer Alexander Taylor (b. 1746), who built much of the country’s early road network. Four barracks went up along the route to garrison it – at Glencree, Laragh, Glenmalure and Aghavannagh. Several survive as ruins; Glencree has been repurposed as the Glencree Centre for Peace and Reconciliation. This is Ireland’s only purpose-built military road of any substance, and with its barracks and largely unaltered line, it counts as a historical monument that still does duty as a working road – an unusual double life for a heritage site.
The section that now forms the R759 across the Sally Gap follows an older east–west track along the Cloghoge River. A higher, exposed alignment here earned the name ‘Murderin’ Pass’ for its treacherous winter conditions, and the name has stuck.
What to See & Do
The stops below come up off lay-bys or short walks along the route.
- Sally Gap – The crossroads at the high point, where the Military Road meets the R759. Get out here: the view is blanket bog, granite and sky, and it feels nothing like the city half an hour north.
- Lough Tay – The ‘Guinness Lake’, so named because the dark water above a pale sand beach looks like a pint of plain. It sits on private Guinness estate land, so viewing is from the roadside only – there is no access to the shore, and no need for any. This is the one stop to make if you make only one.
- P.S. I Love You Bridge – A small stone bridge near the Sally Gap that featured in the 2007 film. A quick photo stop, no more.
- Glencree – The first major stop south of Dublin, with the former barracks and a quiet German war cemetery for sailors and airmen who died off the Irish coast in the World Wars.
- Lower and Upper Lough Bray – Two small glacial lakes a short detour north of Glencree, set under heathery slopes.
- Lough Dan – Visible from the road and reached on forest tracks below.
- Glenmacnass Waterfall – A cascade spilling down the rockface a few kilometres west of the pass, with a small roadside car park and an easy view from the top. Mind your footing on the wet rock above the falls; people have come to grief here.
- Glendalough – The road drops to Laragh, the gateway to the 6th-century monastic city with its round tower, ruined churches and two lakes.
- Powerscourt Estate – Not on the route, but a short hop from Enniskerry to Ireland’s highest waterfall and the formal gardens, if you are building a fuller day.
Walking & hiking
The road is a handy launch point for hill walks:
- Djouce Mountain – From the JB Malone car park near the Sally Gap, a climb to the 724 m summit with a ridge walk and long views across the range.
- Lough Tay to Lough Dan loop – A roughly 10 km circuit on forest tracks from the Lough Tay area, with steady ups and downs.
- Lough Ouler – Accessed from the Glenmacnass car park, a boggy 12 km there-and-back to a remote corrie lake. Sturdy boots, not trainers.
- Ballinastoe Woods – A gentler woodland walk near the northern end, fine for families.
Cycling
The Sally Gap loop (about 26 km on the Military Road and R759) is a serious ride – steep gradients, exposed wind and blind bends, with ice a real risk in winter. Helmet, high-vis and a weather check before you go. Dogs are allowed on the road but must be on a lead.
Food & refreshments
There is nothing on the mountain section itself, so plan ahead:
- Wicklow Heather (Laragh) – Hot food and drinks, useful at the southern end and handy for Glendalough.
- Coach House (Roundwood) – Hearty meals and a fire in winter, off the eastern side of the loop.
Pack waterproofs and something to eat, and don’t rely on your phone – coverage drops out across the bog.
Practical Information
- Opening hours: Open 24/7. Occasionally closed in severe winter weather.
- Admission fee: Free (parking charges may apply at some stops).
- Parking: Informal pull-ins and lay-bys along the route; there are no formal car parks on the mountain section. The Lough Tay viewpoint has roadside space for only eight to ten cars and fills early on summer weekends – arrive before 10am or expect to circle back.
- Road condition: Paved but narrow, with oncoming traffic, blind bends and the odd sheep on the tarmac. Not suitable for wheelchair access beyond the car.
- Winter travel: Snow and ice can close the pass. Check Met Éireann and local signs before travelling.
- Getting there: A car is the practical option; no public transport serves the Sally Gap. Buses reach Rathfarnham and Laragh at either end.
- Guided tours: Day tours from Dublin typically start around €40 and pair the drive with Glendalough.
- Facilities: None on the pass. Nearest toilets and services are at Glendalough, Roundwood or Laragh.
- Dog friendly: Dogs welcome on the road and walks, on a lead within the National Park.
Tip: Morning light is best, as the road faces the rising sun and the bog colours come alive early. Come after a few days of rain and Glenmacnass goes from a trickle to a roar; come in a dry spell and it is a modest step.