The site at Milltown South is a rath, the Irish term for a ringfort, which was a type of enclosed farmstead built and occupied mainly between the sixth and tenth centuries. Thousands of them survive across Ireland in varying states of preservation, though this one has its own particular character, shaped as much by the local geology as by the people who once lived within it.

The enclosure is oval rather than perfectly circular, measuring roughly 25.5 metres north to south and 30.5 metres east to west. It is defined by a bank of earth and stone, and survives best at the eastern and south-western sections, where the bank still stands some 0.6 metres high on its external face. Alongside part of the perimeter runs a fosse, the shallow external ditch that would have added a modest defensive or boundary function to the bank itself. The fosse, where it survives between the east-northeast and the south-southeast arcs, is narrow and not especially deep, around 0.8 metres wide and 0.2 metres deep, though such features inevitably diminish over centuries of agriculture. Towards the south-southeast, the bank loses definition altogether, flattening into something more like a low scarp. The interior slopes gently downward to the east and sits atop an area of outcropping limestone, with the pale grey rock breaking through the turf in places. The record was compiled by Denis Power and uploaded in August 2011.

The site sits in working pasture on a ridge, which means access depends entirely on the landowner's permission, something worth arranging in advance rather than assuming. The exposed limestone in the interior is worth noting underfoot, particularly after wet weather when the ground around it can be soft. The bank is most legible from the eastern side, where the earthwork retains the most height, and walking the perimeter gives a clearer sense of the oval plan than any single vantage point from within. The ridge position, modest as it is, does afford a wider view of the surrounding lowland, which may go some way toward explaining why the original occupants chose this particular spot.