The site at Gortnadrehy sits on a natural rise, and whoever chose this location did so with some care: the elevated ground provides clear views across the surrounding undulating landscape, which would have mattered a great deal to the farming family or minor lord who once lived here.

A rath, the Irish term for a ringfort, was typically a circular or oval earthen enclosure, defined by a bank and ditch, used as a defended farmstead during the early medieval period, roughly the fifth to twelfth centuries. At Gortnadrehy, the defining bank has slumped considerably over time into a broadly sloping scarp, its edges merging almost seamlessly with the natural hillside. The enclosure measures approximately 21 metres north to south and 17 metres east to west. Despite the erosion, the structure still holds its shape in telling ways: the scarp is shallowest on the eastern to south-western side, and a slumped area on the east is thought to mark the position of the original entrance, a common placement in ringforts of this type. Inside, a low residual lip runs along the inner edge of the former bank, giving the interior a faintly saucer-shaped quality, the ground sitting a little lower than the surrounding rim. A thicket of overgrowth has colonised the western edge of the interior, and a disused laneway, its field banks now smothered in vegetation, skirts the base of the slope to the west. Perhaps most intriguing is the proximity of a second rath, recorded approximately 100 metres to the north-east, suggesting that this corner of Mayo once supported a small cluster of enclosed settlements, their occupants neighbours in a landscape that has since been thoroughly rearranged by time.