Somewhere beneath the fields of Beaconstown in County Kildare, three ancient enclosures lie essentially invisible at ground level, detectable only from the air. One of them came to light through a single aerial photograph, designated GB89.R.06, which captured what is known as a cropmark, the faint but telling discolouration that buried archaeological features can produce in growing crops when dry conditions cause vegetation above a filled ditch to ripen or wither at a different rate to the surrounding soil.

What the photograph revealed is a curvilinear enclosure, meaning one with a rounded or irregular outline rather than a straight-sided, geometric form. It was defined by a fosse, essentially a ditch cut into the ground, which would originally have formed a boundary around whatever activity or settlement occupied the interior. This enclosure is one of three adjacent monuments recorded at Beaconstown, sitting close enough together to suggest a concentration of early activity in this part of Kildare, though the precise date and function of the enclosures remains unspecified in what is known about them. Curvilinear enclosures of this general type are commonly associated with early medieval settlement in Ireland, though ringforts, raths, and related forms span a considerable range of periods and purposes. Without excavation, the Beaconstown examples remain quietly ambiguous.