A D-shaped enclosure, roughly 43 metres along its northwest to southeast axis and 38 metres across, sits partially absorbed into a field boundary, its straight western side stretching about 35 metres. That geometric precision, a flat edge on one side and a curved arc on the other, is a hallmark of early enclosures found across Ireland, where such forms often indicate the remains of a ringfort or ecclesiastical enclosure, both typically defined by an earthen bank and ditch encircling a domestic or ceremonial interior.

What makes the Milltown example particularly interesting is the contrast between what the ground shows now and what older maps recorded. The 1900 revision and the 25-inch Ordnance Survey map depict a somewhat different picture: a subrectangular area, smaller at approximately 30 metres by 18 metres, enclosed on its northern, eastern, and southern sides by a band of trees between five and ten metres wide. The trees appear to have been following, or perhaps preserving, the line of an older earthwork, while the western side was left open or had already been lost. Over the intervening decades the enclosure has been partially incorporated into working field boundaries, which is a common fate for such features across the Irish midlands and southeast, where centuries of tillage and land reorganisation have quietly dismantled or reoriented ancient earthworks without entirely erasing them.