|Location Map ( geo)|
|Distance:||40.8 km (25.4 miles)|
|Meets:||R114, R821, R817, R113, R116, R759, R755|
The R115 runs south from the R114 in Rathfarnham, South Dublin, through the Wicklow Mountains – via Glencree and the Sally Gap, where it forms a crossroads with the R759. From there it goes for a further 19.5 km through scenic uplands to the village of Laragh, lying close to the ancient monastic site of Glendalough on the R755 in County Wicklow.
For the greater part of its length the route follows the Old Military Road, constructed for the purposes of repression in 1801–1809. Much of the route is more than 400 m above sea level and about four kilometres north of the Sally Gap it reaches an altitude of 520 m; consequently it is liable to closure during periods of severe winter weather.