It only became apparent from the air, when a dry summer caused the crops above it to ripen unevenly, tracing the outline of an ancient feature in the soil below. This is how cropmarks work: buried ditches retain moisture differently from the surrounding ground, and in the right conditions that difference shows up as a faint variation in plant growth, legible only from altitude and only for a brief window of the year.

The feature recorded here is a ring-ditch, a type of small circular enclosure defined by a fosse, or ditch, cut into the earth. This one measures roughly five metres in diameter, which places it at the smaller end of the scale for such monuments. Ring-ditches are generally understood to be the ploughed-down remains of Bronze Age burial mounds, the surrounding ditch once marking the edge of a barrow that has long since been levelled by centuries of agriculture. What makes Blanchvillestown particularly interesting is its density. A larger ring-ditch sits approximately eight metres to the north-north-west, and a third lies some twenty-six metres to the south-south-east. Three such features within such a compact area suggests this was once a deliberate funerary landscape, a cluster of monuments that may have marked family or community burials over generations. The aerial photographs that revealed all of this were taken on 22 July 2000, midsummer, when the conditions for reading buried archaeology from the air are often at their sharpest.