A rath, the Irish term for a ringfort, a roughly circular earthen enclosure typically used as a defended farmstead during the early medieval period, once sat on a gentle north-west-facing slope here. It measured around forty metres across. Today it survives as little more than a slight rise in the ground, a shallow platform that most walkers would pass without a second thought.

The structure was levelled during the 1960s, a fate shared by a great many Irish ringforts during the post-war decades of agricultural intensification, when earthworks were cleared to improve grazing or tillage land. What makes the Coolroe example useful to historians is the paper trail left by the Ordnance Survey. Both the 1846 and 1894 six-inch OS maps show the site clearly as a circular enclosure of roughly forty metres in diameter, with field boundaries already crossing the eastern sector by the time those surveys were made. The maps confirm that the enclosure was a recognisable feature of the landscape for at least a century before it was finally erased, and they preserve the shape that the ground itself no longer quite holds.

The slightly raised area that remains today measures approximately forty metres north to south and thirty-eight metres east to west, sitting in level pasture on the hillock's lower slope. A north-south field boundary still cuts across the eastern part of the site, as it did when the Victorian surveyors recorded it. There is no dramatic earthwork to read from a distance, but the faint platform is there for anyone who knows to look for it.