They came to light only when the proposed widening of the N11 between Newtownmountkennedy and Ballynabarny prompted an archaeological investigation of the land in its path.

Fulachta fiadh, the plural of fulacht fia, are among the most common prehistoric monument types in Ireland, low horseshoe-shaped mounds formed from the shattered residue of repeated heating. The standard interpretation is that stones were heated in fire and then dropped into a water-filled trough to bring the contents to a boil, though debate continues about whether this was primarily for cooking, bathing, or other industrial processes. At Ballynabarny, preliminary testing by Ruth Elliot in October 2001 identified the site's potential, and subsequent excavation revealed two substantial mounds on the highest part of the eastern slope, at between 105 and 110 metres above sea level. The southern mound measured at least 13 metres in diameter and covered one probable trough cut into the ground beneath it. The northern mound, at least 10 metres across, was more complex, with three probable troughs beneath it, a further probable trough beside it, and a smaller pit nearby. Beneath the northern mound, excavators also found what appeared to be four parallel agricultural furrows with possible ard-marks, the shallow scoring left by an early plough-like implement dragged across soil, running down the slope at intervals of 1.5 to 2 metres. One of the troughs had been cut directly through one of these furrows, suggesting the farming activity predated even the mound-building. Scattered within 30 metres of both mounds were smaller features containing burnt material, and a fragment of pottery recovered from one of them was provisionally dated to the Bronze Age, a date considered most likely for the whole group. A separate cluster of up to twelve pits or post-holes was identified on the western part of the hillside, in no discernible pattern, and may also be prehistoric in origin, though their purpose remained unclear.