The site at Knockanea is a rath, the Irish term for a ringfort, which was the standard form of rural settlement in early medieval Ireland, typically enclosing a farmstead within a raised earthen bank and ditch. What makes this one worth pausing over is its modest but legible geometry: an almost circular platform, roughly 21 metres across its longer axis, still defined by a scarped edge, that is, a deliberately cut and shaped slope, rising to about 0.9 metres. Outside that edge, a fosse, or defensive ditch, runs from the south around to the north, still traceable on the ground at around 3.5 metres wide and 0.3 metres deep. The interior tilts gently down toward the north-east, which may reflect how the original occupants managed drainage or simply how the ground has settled over the centuries.

The site appears on the 1923 Ordnance Survey six-inch map under the name Lisnagroagh, a placename that carries within it the Irish word lios, another term for a ringfort enclosure. The record was compiled by Denis Power and uploaded to the national monument database in June 2013. Beyond its name on that century-old map and its measured dimensions, the documentary record is thin, as is the case with the great majority of the estimated 45,000 or so ringforts that survive across Ireland. Most were the homes of farming families of middling rank during the early medieval period, roughly the fifth to the twelfth centuries, enclosed for the protection of livestock as much as people.

The fort sits at the base of a north-east-facing slope in gently rolling pasture, and the notes record good views in all directions, so the approach on foot across open farmland gives a reasonable sense of how the site relates to its surroundings. The curving field boundary immediately to the south-east is itself worth noting; boundaries like this often fossilise the outline of much older enclosures and can persist in the landscape long after the earthwork they once followed has been ploughed or grazed down. The scarped edge and fosse are the features most likely to be legible on the ground, and they are best read in low winter or early spring light, when shadows pick out shallow relief that disappears entirely in summer growth.