A ringfort, or rath, is an enclosed farmstead of the early medieval period, typically circular and bounded by one or more earthen banks and ditches. At Coolcloher, almost all of that structure is gone, yet the site refuses to disappear entirely. A low rise, no more than 0.6 metres at its highest external point, traces a circle roughly 29 metres across, and faint depressions to the north-west, north, and east hint at where a surrounding ditch once sat.

The site was already compromised by the time cartographers recorded it. The 1842 Ordnance Survey six-inch map shows a hachured circular enclosure of approximately 25 metres in diameter, the standard graphic shorthand of the period for earthwork features. The discrepancy between that earlier measurement and the 29 metres noted in more recent fieldwork likely reflects how the boundaries of a degraded earthwork are read differently as material continues to spread and settle. Bowman, writing in 1934, documented what he described as a levelled single-ramparted fort of around 29 yards in diameter on land belonging to a M. Hegarty, confirming that the earthwork had already lost most of its definition by the early twentieth century. What we have now, then, is a site that has been quietly eroding for at least the better part of two centuries.

The field itself sits on nearly level ground, which is unusual in a landscape where raths are more often positioned to take advantage of elevated or sloping terrain. That flatness may partly explain why the enclosure was so susceptible to agricultural clearance. The surviving rise is slight enough that without knowing where to look, the geometry of the place is easy to miss.