The ground drops away steeply to the east, opening a long view over low-lying, waterlogged fields, and it is hard not to feel that this orientation was entirely deliberate. A rath, the Irish term for a ringfort, is essentially a circular or oval enclosure defined by an earthen bank and external ditch, and was typically the farmstead of a moderately prosperous family during the early medieval period, roughly the fifth to twelfth centuries. What makes the Garrycloonagh example quietly worth attention is not just its good state of preservation but its setting within what appears to have been a small local cluster of such enclosures.

The rath measures roughly 33 metres north to south and somewhere between 37 and 38 metres east to west, enclosed by an earthen bank approximately five metres wide. The bank stands about 0.8 metres above the interior ground level, and rather more on its outer face, reaching at least two metres on the eastern side where the slope is steepest. Around the circuit runs an external fosse, a ditch roughly four metres wide and 0.7 metres deep, most clearly defined between the south-west and north-west. Elsewhere it has been reduced to a barely perceptible depression, and along part of its outer edge a later field fence has been built, casually annexing the ancient boundary into the modern agricultural landscape. There are narrow, eroded breaks in the bank at several points, but a broader gap of about three metres at the south-east is the most likely candidate for the original entrance. Two boulders sit just inside the bank to the north of this gap, and a considerably larger one rests against the inner face of the bank to the west; their original purpose, if any, is unclear. The whole circuit is now fringed densely with blackthorn and brambles. Roughly 230 metres to the west lies another confirmed rath, and a possible third example sits around 290 metres to the north-west, suggesting this particular patch of Mayo was once something closer to a settled neighbourhood than an empty field.