What remains is written in grass. In dry conditions, the soil above its former earthworks holds moisture differently from the surrounding pasture, producing patches of yellowing growth that trace the shape of the original structure with quiet precision. A ring barrow is, broadly speaking, a burial mound encircled by a bank and ditch, a funerary form found across Ireland from the Bronze Age onward. At Gortnasillagh, even the levelled remnant carries that essential geometry: a roughly D-shaped area of approximately fourteen metres east to west and fifteen metres north to south, defined by an intermittent band of yellow grass about two metres wide, and, near the centre of the enclosed space, a separate circular patch roughly five metres across, with a clear gap between it and the outer band.

The site appears on the Ordnance Survey six-inch map of 1838 as a circular embanked enclosure between fifteen and twenty metres in diameter, its northern edge already bordered by an east to west field boundary. By the 1931 edition of the same mapping, cartographers had added a hachured sunken feature, a conventional symbol for a hollow or depression, suggesting the interior had by then begun to subside or had been deliberately disturbed. At some point after that the bank was levelled entirely, probably as part of ongoing pastoral land management. A laneway now cuts across the northern edge, truncating the monument on its straight side and accounting for the D-shape rather than the full circle that the earlier maps recorded. The cropmarks visible today may be all that is left of that original circular enclosure, preserved not in earth but in the seasonal behaviour of the grass above it.