This one, in Rathmore, County Wexford, does none of that. It exists, for most practical purposes, only from the air. A faint cropmark, roughly circular and about 25 metres across, is all that betrays it, the ghost of a fosse, a rock-cut or earthen ditch, pressing through a cereal crop in a way the human eye at ground level simply cannot read.

A rath, or ringfort, was typically a farmstead of the early medieval period, enclosed within one or more circular banks and ditches to define a household's territory and protect livestock. Thousands of them survive across Ireland in varying states of preservation, but a significant number have been reduced, over centuries of ploughing, to precisely this condition: invisible to anyone standing in the field, yet legible to a camera carried overhead at the right season and angle. When crops grow over a buried ditch, the roots reach deeper moisture and nutrients, and the plants above grow fractionally taller or greener, tracing the outline of the old feature in the living grain. What is unusual about this particular site is the concentration of early settlement around it. At least three further rath sites have been recorded within 100 to 200 metres to the east, south, and west, suggesting that this flat stretch of Wexford farmland was, at some point in the early medieval centuries, rather densely occupied.