A ringfort, or rath, is a roughly circular enclosure defined by an earthen bank and ditch, built during the early medieval period as a defended farmstead. Thousands survive across Ireland, but this one at Rosnamulteeny carries an unusual complication: the outer bank, which is faced internally with stone, may not be early medieval at all.

The enclosure measures twenty-six metres in diameter and is defined by an earth and stone bank, modest in scale, rising about half a metre on the interior and just under a metre on the exterior side, with an outer fosse, or ditch, three metres wide and half a metre deep running around it. The entrance gap, just over three metres wide, opens to the south-east. That much fits the typical pattern of an Irish rath. The complication lies in the outer bank with its stone facing, which archaeologists have suggested may date instead to the nineteenth century, constructed as a field boundary in connection with a farmhouse nearby. The possibility that a later farmer quietly incorporated or remodelled part of an older monument into a working boundary is not unusual in the Irish landscape, where ancient earthworks were often pressed into practical service without anyone recording the fact. A second ringfort lies a short distance to the south, making this part of Rosnamulteeny a cluster of early medieval activity, whatever the precise date of the disputed stonework.