What they might be crossing, however, is a ringfort, one of the most common yet persistently underappreciated monument types in the Irish landscape. Thousands survive across the country, and this one announces itself only through a low, encircling scarp, a kind of earthen step roughly 0.9 metres high, tracing an oval shape approximately 36 metres north to south and 40 metres east to west.

Ringforts, known in Irish as raths, were the farmsteads of early medieval Ireland, typically dating from somewhere between the sixth and twelfth centuries. They served as enclosed homesteads, the surrounding bank and ditch providing a degree of security for people and livestock rather than representing any serious military fortification. At Cornalassan, faint traces of an inner bank, surviving to around 0.3 metres and running from the north-west to the north-east, suggest the site may once have had more substantial internal features, though these have largely been absorbed back into the ground over the centuries. The classification remains cautious, described only as probably a ringfort, which is itself a reasonable reflection of how much these sites can soften into the surrounding terrain over a thousand or more years of grazing, ploughing, and weather.