It is easy to miss: the earthen bank barely rises half a metre at its highest point, and the enclosure it once defined, roughly 21 metres north to south and 23 metres east to west, is now more felt than seen, a gentle interruption in the slope of the land rather than anything obviously architectural.

What survives is a rath, the most common type of ringfort found across Ireland, typically constructed between the sixth and tenth centuries as a defended farmstead for a single family of some local standing. A low circular or oval earthen bank, sometimes accompanied by an external ditch called a fosse, enclosed a domestic space where houses, animals, and stores would have been kept. At Cloonkeen, the bank is still traceable to the north, east, and south of the enclosure, and a shallow depression running just outside it may be the eroded remains of exactly such a fosse. Intriguingly, a field boundary running roughly north-northeast to south-southwest has been laid out in a way that respects the line of the old enclosure, suggesting that even as the rath lost its original function, later farmers recognised its outline and worked around it rather than through it.