At the crest of a low ridge in Ballygunnermore, County Waterford, a large oval earthwork sits quietly in the landscape, known to local people by the old Irish word lios, a term used for a ringfort or enclosed settlement of early medieval date. What makes this particular enclosure quietly compelling is that it exists in two registers at once: as a physical embankment still legible on the ground, and as a ghostly double of itself visible only from the air, where aerial photography has revealed the cropmark of a second, circular line of enclosure beneath the soil, suggesting that what appears to be a single monument may in fact preserve the traces of an earlier or differently shaped structure beneath.

The enclosure was already recorded on the Ordnance Survey six-inch map of 1840, which gives some measure of how long it has held a place in the documented landscape. Its outer dimensions run to roughly 75 metres north to south and 65 metres east to west. The Reverend P. Power noted it in the Journal of the Royal Society of Antiquaries of Ireland in 1887 to 1888, identifying it as Casey's lios, the local name anchoring it to a particular family or landholding of the time. Aerial photography later showed that beneath the visible bank lies the cropmark of a bivallate enclosure, meaning one defined by two concentric ditches or banks, with an external diameter of around 70 metres. The perimeter on the east and south-east has been absorbed into a later field bank, which is a common fate for ancient earthworks in farmed landscapes. Most significantly, a souterrain was discovered within the eastern bank. A souterrain is an underground stone-lined passage or chamber, typically associated with early medieval settlement, used for storage or possibly refuge, and their presence within or beside ringforts is well attested across Ireland.