Sitting quietly in pasture in mid Cork, a circular earthwork roughly 25 metres across survives as a low bank of earth and stone, standing about 1.2 metres high. It is the kind of feature that a person might walk past without a second thought, mistaking it for a field boundary or a natural rise in the ground. But it is a rath, the most common type of early medieval enclosure in Ireland, typically formed by throwing up a bank and digging a surrounding ditch, or fosse, to define a defended farmstead. At Lacknahaghny, the bank is still there. The fosse is not.

When P. J. Hartnett recorded this site in 1939, the external fosse was still visible. By the time the mid Cork archaeological inventory was compiled in the 1990s, it had gone, most likely levelled by decades of agricultural activity. Hartnett's observation, published in 1939, provides a small but useful anchor: it tells us the site once had the full complement of features expected of a rath, the enclosing bank thrown up from material dug out of the ditch immediately outside it. The disappearance of that fosse in the intervening years is a reminder of how quickly even earthworks of this age, which may date back to the early medieval period, can be eroded or obscured once the land around them is in regular use.