By the time a later realignment was made, that consideration had been abandoned, and the road now bisects what remains of a ringfort that once measured roughly 45 metres across. It is a small, telling detail: an estate driveway that first acknowledged a prehistoric monument, then quietly erased half of it.

Ringforts, known in Irish as raths or lios, are the most common archaeological monument in Ireland, typically circular enclosures of earth or stone built during the early medieval period as farmsteads or high-status residences. This one, on a west-facing slope just above the Finnow stream, was clearly visible on the Ordnance Survey's six-inch map of 1842, shown as a hachured circular enclosure, the hachures being the fine radiating lines surveyors used to indicate a scarp or raised bank. The same feature, reduced to a single arc of earthwork running NNW to SSE, still appeared on OS maps from 1905 and 1936, the avenue to Rathnee House at that point still respecting its outline. At some stage afterwards, the avenue was realigned and the site substantially levelled. What survives today is a circular area of roughly 31 metres in diameter, defined by a scarp about 0.95 metres high to the south-east, with a shallow external fosse, the ditch that would once have ringed the outer edge of the bank. Fainter traces of a second fosse can be read to the west and north-west, continuing as differential crop growth around to the east-north-east. Taken together, these traces suggest this may be the double-ramparted ringfort of around 33 yards diameter that a researcher named Bowman recorded in 1934 on land then belonging to H. Deady, noting an inner rampart of roughly eight feet in height and a saucer-shaped interior, with the outer rampart already gone even then.