The bank is long gone, ploughed or pushed flat at some point in the agricultural past, yet the outline of the enclosure persists in the soil beneath, colouring the pasture above it in a way that only becomes legible when you know what to look for.

Ringforts, sometimes called raths, were the most common form of enclosed settlement in early medieval Ireland, typically consisting of a circular bank and ditch surrounding a farmstead or homestead. The example at Coolrus, on a south-east-facing slope, was still visible as an embanked circular enclosure on the Ordnance Survey six-inch map of 1923, with a recorded diameter of around 25 metres. By the time fieldwork compiled by Denis Power was recorded and uploaded in August 2011, the bank itself had been levelled entirely. What remained was a circular band of discoloured vegetation roughly 4.5 metres wide, enclosing an area measuring approximately 36 metres north to south and 35 metres east to west. A faint trace of a fosse, the external ditch that would originally have reinforced the bank, survives at the north-west, just 10 centimetres deep and around 4.5 metres wide, barely a crease in the ground.

The site sits in pasture, which is part of why anything survives at all. Grassland tends to preserve these ghost-outlines better than arable ground, since repeated ploughing would have erased even the soil discolouration. A visitor would find no signage and no formal access, and the feature is the kind of thing that rewards patience and a careful eye rather than a quick glance from a road. The yellowed band is most legible in dry summer conditions, when differential moisture retention in disturbed or compacted soils shows up clearly in the vegetation above. If you are in the area and looking at a gently sloping field, the faint circle in the grass is the whole of what remains.