In a level field of improved pasture in Dunnstown, County Kildare, there is nothing to see. No ridge, no hollow, no scatter of stone suggests that anything of human making ever occupied this ground. And yet, from the air, the soil tells a different story. Six small, roughly rectangular earthworks appear here as cropmarks, the kind of subtle discolouration in growing crops or parched grass that betrays buried features to a camera carried high enough to catch them.

Cropmarks form because buried walls, ditches, or filled pits affect how deeply plant roots can grow and how much moisture they can reach. Over a filled ditch, crops grow taller and greener; over a buried wall, they may be stunted and pale. The effect is invisible at ground level but can resolve into clear outlines when photographed from the air, particularly during dry summers. At Dunnstown, a single aerial photograph, catalogued as GSI N 337-6, revealed all six enclosures at once. They are arranged in two roughly parallel rows of three, the whole group occupying a roughly rectangular area of approximately 150 metres on its northwest to southeast axis and around 100 metres across. The enclosures themselves are small and broadly rectangular in form. What they were used for, and when, the aerial record alone cannot say.