A rath, to use the Irish term, is a roughly circular enclosed settlement, typically dating from somewhere between the sixth and tenth centuries, defined by earthen banks and ditches that once surrounded a farmstead or a small community. Here, however, the builders appear to have done what good engineers always do: used what the land already offered. Rather than throwing up substantial artificial banks from scratch, they placed the enclosure on top of a natural knoll, a low spur projecting northward from a gentle east-to-west ridge, and let the steep natural slopes do most of the defensive work.

The oval interior measures roughly twenty-five metres north to south and thirty metres east to west, a modest but workable space. On the western and northern sides, the knoll drops away sharply, reaching a height of around three and a half metres at the north, and this natural scarp forms the primary enclosure on those sides. A short stretch of man-made scarp survives to the northeast, standing about one and a half metres, though it fades out before reaching the east. On the southern side, a very slight scarp suggests where the perimeter once curved round, though it is barely thirty centimetres high now. The eastern side, where the knoll merges more gradually with the surrounding ridge, has no clearly surviving enclosing element at all. That the interior is level and featureless today is typical of long-pastured ringforts; centuries of grazing animals and weather tend to erase whatever traces of structures once stood inside. Local tradition, passed on by a resident of Rathroe in 2016, still calls the site a fort. About two hundred metres to the southeast, on the eastern bank of the Rathroe River, stands Rathroe Castle, a tower house of a much later period, suggesting that whoever controlled this valley found the same ground worth occupying across several different centuries.