For a few hundred metres near the top of the valley, its original surface remains exposed: flat stones up to a metre across, carefully fitted together and chinked with smaller stones in the gaps, climbing a gradient steep enough to rule out carts or any wheeled traffic. Large earthfast boulders protrude through the surface at intervals, further confirming that this was a route for horses and people on foot. The track is about three metres wide for much of its length, bordered by low earthen banks on either side and a drainage ditch on the uphill flank, though sections are overgrown, buried under mine spoil, or quietly absorbed into working farmland. At least 2,350 metres can be accounted for, but only around 750 metres of that can still be traced near the north-western end.

The road takes its name from St Kevin of Glendalough, the sixth-century monastic founder whose settlement lies a short distance to the south-east, and the route almost certainly served pilgrims travelling to that site across the mountains. On Nevill's map of County Wicklow, drawn in 1760, it appears as the only road through Wicklow Gap, suggesting it was still a functioning thoroughfare at that date. Price, writing in 1940, noted that it continued north-westwards beyond the gap towards Templefinan church in Ballinagee townland, a detail not shown on the Ordnance Survey six-inch maps. The present county road through Glendasan was built around 1826, and Wright's guide to Wicklow in its 1827 edition mentions a road then under construction through the gap. By 1837, Lewis could record a new road completed between Glendalough and Hollywood. Small excavations were carried out along the route by the National Museum of Ireland in 1968 and 1972, and University College Dublin conducted further investigations in 2005 and 2006.

Running higher still above Glendasan, and entirely separate from St Kevin's Road, is a stranger feature altogether. Known locally as the Madman's Road, this unfinished track stretches over 6.5 kilometres along the side of Brockagh Mountain, beginning around the 700-foot contour opposite the Royal Hotel and ending inconclusively on the slopes of Tonlagee Mountain. It is roughly four metres wide, reasonably well graded, and equipped with stone culverts, yet it was apparently never used. Wet boggy sections remain uncausewayed, and the gaps in the route were never bridged. Drill marks from explosives are still visible on some of the split stones. Wright's Wicklow map of 1822 shows a road following this same line, and the most plausible explanation links it to the lead mines at Luganure, where a trial shaft was recorded in 1800 and where the Mining Company of Ireland began full operations in 1826. The working mine shafts sat well below the level of the Madman's Road, and once the valley-floor route was built, the higher track became unnecessary. It was abandoned mid-construction, and has remained so ever since.