The cairn measures roughly twenty-two metres across and rises five and a half metres above the slope of Ben Langass. From a distance it reads as a low stony bump against the heather - easy to miss if you don't know what you're looking for. Up close the scale becomes clear. The east-facing entrance leads into a chamber whose ceiling is formed by those two enormous slabs, with a third piled across them like a careless afterthought, although nothing here was careless. The structure has partly collapsed, but enough survives that a person with a torch and a willingness to stoop can still enter the chamber and stand where mourners stood when bronze was not yet imagined.

Erskine Beveridge - textile manufacturer, antiquary, and Vallay resident - dug into Barpa Langass in or just before 1911. What he found inside the chamber confirmed it as a burial place: evidence of burnt bones, pieces of pottery decorated with patterned lines, wood ashes, a flint arrowhead, a stone scraper, and a curious piece of pierced talc. Beveridge believed two and perhaps three chambers existed within the cairn, though only one is reachable today. His finds are the small intimate residue of people who farmed this hillside in the Neolithic - their tools, their pots, the cremated remains of whoever was important enough to be brought up the hill.

The cairn sits five miles southwest of Lochmaddy, reached by a footpath leaving the A867 - the main north-south road across North Uist. The classic walk starts lower down at the Langass Lodge Hotel, follows the trail to the Pobull Fhinn stone circle on the south slope of the same hill, then continues uphill to Barpa Langass. The route takes you through both a ceremonial monument and a burial monument from the same prehistoric culture, on the same small hill, in roughly the order the builders might have visited them. The wind is usually doing something. The view stretches across Loch Langass to Eaval beyond, and on a clear day the islands of the inner Hebrides are visible to the east.