What makes it worth attention is the fact that it is bivallate, meaning it was constructed with not one but two concentric defensive banks, a design that suggests its original occupants considered extra protection worthwhile, or perhaps that they held enough social standing to invest in the more elaborate form. Most ringforts across Ireland are univallate, a single bank enclosing a roughly circular area, so the presence of a double circuit here marks this site out from the majority.

The ringfort measures approximately 28 metres in diameter and is defined by an inner earthen bank roughly 3 to 3.5 metres wide and 0.3 metres high, followed by an external fosse, a ditch that would have added both a physical and a psychological barrier to anyone approaching, and then an outer bank some 2 metres wide rising to 0.8 metres. Ringforts, known in Irish as raths when constructed primarily of earth, were the most common form of rural settlement in early medieval Ireland, typically housing a farming family and their livestock within the enclosed space. The Rosnastraw example has yielded no clear evidence of an entrance and no visible internal features remain, which is not unusual given how thoroughly vegetation can obscure such details over centuries. The northeastern edge of the site is clipped by a lane lined with earthen banks, a small intrusion that hints at how quietly agricultural life has continued to press against and around these older boundaries.