The one at Ballyreilly in County Wexford has largely surrendered that visibility, existing now as little more than a shadow in the soil, readable only from the air.

What survives at Ballyreilly is a cropmark fosse, the buried trace of what was once a defensive ditch surrounding the settlement. Cropmarks form when buried features affect the growth of whatever is planted above them, producing variations in colour and height that become legible in aerial photographs taken during dry summers, when the differences are sharpest. In this case, the arc of the fosse appears in aerial photographs as a D-shaped enclosure, roughly 30 metres across in both its north-east to south-west and north-west to south-east dimensions, with a pre-existing field bank forming the straight side to the north-east. That straight side is what gives the enclosure its D-shape, suggesting that when the ringfort was constructed, its builders incorporated or worked around a field boundary that was already present on this fairly level piece of ground.