They are visible from the air, captured in a 2011 aerial photograph, and they sit in a landscape so thoroughly reshaped by post-1700 estate planning that it is genuinely difficult to say what they are. Barrows, in the prehistoric sense, are burial mounds, low circular earthen structures that in Ireland often date to the Bronze Age. These might be exactly that. Or they might be ornamental mounds created by a Georgian-era landscaper with an eye for symmetry and a fondness for grove planting. No one has yet settled the question.

The uncertainty is sharpened by the company these earthworks keep. A ringfort, one of the enclosed circular farmsteads that dot the Irish countryside from the early medieval period, sits about 90 metres to the north, and two other recorded landscape features lie not far beyond that. A post-1700 monument of some kind was erected on the demesne roughly 270 metres to the north-north-east. Killua Castle itself, a substantial Anglo-Irish estate, is around 570 metres away in the same direction. The first-edition Ordnance Survey six-inch map, surveyed in the 1830s, shows tree groves and an old pathway threading through this part of the deerpark, and marks a separate "Old Deer Park" about 650 metres to the south. All of this suggests a landscape that was deliberately composed and planted by the castle's owners after 1700, which means the earthworks could have been incorporated as picturesque features, or may simply have been left in place because they were already there and made useful focal points among the trees. The ambiguity is the point: the same low mound can accumulate meanings across millennia without any single one cancelling the others out.