Near Hobartstown in County Kildare, somewhere beneath ordinary agricultural land, lies an arrangement of ancient boundaries that is almost entirely invisible from the ground. The only way to see it clearly is from the air, where the buried geometry betrays itself through the crops above it. Where soil was once disturbed by digging, it retains moisture differently, and that difference shows up in the growth of whatever is planted there. The result is a cropmark, a faint but legible signature left by something long buried, and in this case the signature is striking in its complexity.

An aerial photograph taken in 1996 revealed two distinct enclosures at this site. The larger of the two is rectilinear, defined by a fosse, which is simply a ditch or trench dug into the earth, typically as a boundary or defensive feature. Immediately to the south-west of it sits a second enclosure, this one circular in form, though incomplete, its fosse tracing only part of a curve before stopping. The combination of a large rectangular enclosure alongside a partial circular one is unusual. Rectilinear enclosures of this kind in Ireland are sometimes associated with early ecclesiastical settlements or high-status secular sites, though the evidence here does not point firmly in either direction. What is clear is that whoever laid out these boundaries was working at a considerable scale, and that the two enclosures were almost certainly related to one another in some deliberate way.

Because the site exists as a cropmark rather than as any visible surface feature, there is nothing to see from the road or on foot. The enclosures have not been excavated, and no objects or structural remains have been recovered from them as far as the available record shows. The site endures as a shape, preserved accidentally in the chemistry of the soil and readable only under the right conditions of light, crop growth, and altitude.