Stand in the fields of this part of County Dublin and the ground offers no hint that anything lies beneath it, no earthwork, no rise in the soil, no stones protruding from a hedgerow. The site is entirely invisible at ground level, belonging instead to a category of monument that only reveals itself from the air, under the right conditions, in the right season.

The enclosures at Kilmartin came to light through aerial photography carried out by Dr Gillian Barrett in the 1980s. Cropmarks, which appear when buried features affect the growth of crops above them, showing as lighter or darker bands in a field when seen from altitude, revealed at least three separate enclosures, each averaging roughly 60 to 70 metres in diameter. A portion of what appears to be an outer boundary element was also discernible at the westernmost of the three. Decades later, a geophysical survey was carried out under licence (11R0152), followed by test excavation in 2012 (licence 12E0063). That excavation, reported by Kavanagh, uncovered a linear feature measuring 1.5 metres wide and 0.4 metres deep, running along a line that matched the southern side of one enclosure, suggesting it formed part of the monument itself. Whether these are the remains of a settlement, a ritual site, or something else entirely remains an open question.

Because there is no surface trace, a visit here is less about what you can see and more about what you know is there. The site is most legible, in the literal sense, from aerial images rather than on foot. For those interested in the archaeology, consulting the published geophysical survey results or Kavanagh's 2012 report would give a clearer picture of the subsurface layout than any amount of walking the field. Cropmarks, where visible, tend to show most clearly in dry summers when differential soil moisture brings buried ditches and banks into contrast with the surrounding ground, but that requires the right vantage point and conditions that cannot be guaranteed.