This one in Cahirduff, County Limerick, does the opposite: it has left no trace at all on the ground, and yet it exists in the record, logged and numbered, a feature that the landscape has entirely swallowed. What makes it curious is precisely this absence. It was never drawn on the Ordnance Survey's meticulous 6-inch map of 1840, nor on the more detailed 25-inch revision of 1897, suggesting that even in those periods of systematic cartographic coverage, there was nothing obvious enough to warrant marking. The enclosure's existence was established not by fieldwork or excavation but by a careful reading of aerial photographs.

The site came to light in 1986 during preparatory survey work for the Curraleigh to Limerick gas pipeline, when analysts examining aerial photography at a scale of 1:10,000 identified a feature on a slight north-facing slope, roughly ninety metres west of the townland boundary with Ballymartin. Aerial survey of this kind can reveal cropmarks or soilmarks, subtle variations in vegetation or soil colour that reflect buried features beneath the surface, structures that cast no shadow and leave no upstanding stonework but still influence how the ground above them behaves in dry summers or at particular angles of light. When the Archaeological Survey of Ireland visited the location in 2000, there was nothing to see at ground level. A more recent check against a Google Earth image captured in February 2020 confirmed the same: no visible trace remains.

For anyone curious enough to go looking, the site sits within the townland of Cahirduff in County Limerick, close to the boundary with Ballymartin. The field record compiled by Martin Fitzpatrick and uploaded to the national monuments database in August 2020 is, in a sense, the only tangible form this enclosure now takes. There is no visitor infrastructure, no interpretation panel, and nothing to see on arrival. What the site offers instead is a quiet lesson in how archaeology works: that absence of evidence is not the same as evidence of absence, and that a pipeline survey conducted with aerial photographs can locate something that two generations of Ordnance Survey mapmakers walked past without recording.