There is nothing to see at Skerries in County Kildare, and that is precisely what makes it interesting. The field here is level, improved tillage land, and whatever once occupied this ground has been thoroughly erased. No bank, no hollow, no trace of stonework interrupts the surface. Yet something was here, and overhead photography has kept insisting on the fact for more than fifty years.

By 1909, the second edition of the Ordnance Survey six-inch map recorded a raised oval area, roughly fifty metres across its north-east to south-west axis and about forty-five metres in the other direction, defined by a scarp. That feature was absent from the first edition of 1839, though that absence likely reflects the limits of early surveying rather than any real change on the ground. By the time the 1909 map was drawn, field boundaries and woodland that once surrounded the site have since been removed, and the raised area itself has been levelled entirely. What survives is a cropmark, the faint differential in how crops grow above buried features, a fosse being an enclosing ditch, where disturbed or moister soil can show up in aerial photographs as a slightly different tone or growth pattern. A 1968 aerial photograph, taken as part of the Cambridge University Collection of Aerial Photography, captured exactly this: the ghost of a roughly circular enclosure just legible from the air. Dr. Gillian Barrett photographed the same cropmark again in 1990. More recently, imagery from 28 June 2018 shows not one but two circular cropmarks at the location, a detail brought to attention by Anthony Murphy, whose work tracing monuments through aerial and satellite imagery has helped document sites like this one across Ireland.

Because no surface trace remains, there is little to observe from ground level. The cropmarks are best appreciated through the aerial imagery rather than a visit to the field itself, and the character of the enclosure, its date, its function, and its relationship to the second ring visible in the 2018 imagery, remains unexcavated and open.