This one exists only in a single aerial photograph, taken in 1949, over undulating pasture near the southern bank of the Glanrastel River in south-west Kerry. What the camera captured was a cropmark, the faint but legible outline of an oval enclosure roughly 40 metres north to south and 25 metres east to west. Walk the same ground today and there is nothing to see.

Cropmarks form when buried features, old ditches, filled-in pits, the ghostly footprint of a long-vanished wall, influence how grass or grain grows above them. Soil over a buried ditch tends to retain more moisture and produce lusher, taller growth; soil compressed by an ancient foundation does the opposite. From the air, and usually only under the right combination of dry weather and low sun, these differences become visible as tonal variations in vegetation. The photograph in question, catalogued as ACAP V 164/67-68, caught this particular enclosure at precisely such a moment. Since then, no corresponding feature has been recorded at ground level, which means everything known about its shape, its orientation, and its approximate dimensions depends entirely on that one flight over Kerry more than seventy years ago.