A ringfort, known in Irish as a rath when built from earth rather than stone, was the standard enclosed farmstead of early medieval Ireland, typically dating from roughly the fifth to the twelfth century. Most were home to a single farming family, the enclosing bank and fosse offering a degree of status and security rather than serious military defence. This one is roughly circular, measuring about 29 metres north to south and 34 metres east to west, with a surrounding bank nearly eight metres wide and rising almost two metres above the outer ground level on its exterior face. Beyond that bank, a fosse, a cut defensive ditch roughly two and a half metres wide and just over a metre deep, once ran the full circuit, with a smaller outer bank visible at least along the northern arc.

What makes this particular site instructive is what has happened to it since it ceased to be used as a settlement. A field boundary that once ran east to west along the southern side of the ringfort was levelled at some point, and the spoil was pushed into the monument itself. The southern and western quadrants have suffered most, with that dumped material filling in the fosse and burying the outer bank so that the earthwork reads as simpler than it actually is. A four-metre gap in the western bank may represent an original entrance, or it may itself be a result of later disturbance. Scrub has colonised the southern bank, and trees have taken hold in the northern sector, so the visible profile of the site shifts considerably depending on where you are standing. The place-name Rathcool preserves the Irish word rath in its first syllable, a reminder that this kind of monument was prominent enough in the landscape to give its name to the surrounding townland.