They show up only from above, as faint circular shadows in aerial photography, the kind of detail that can pass unnoticed for generations until someone looks at the right image at the right moment.

The site was identified by Jean-Charles Caillère from satellite imagery and consists of a circular enclosure roughly 34 metres in diameter, its outline traced by a fosse, a defensive or boundary ditch cut into the earth. Set within it, but not quite centred, sitting closer to the northern edge, is a second smaller enclosure of around 20 metres across, also defined by its own fosse. The off-centre positioning of the inner ring is quietly puzzling. Concentric enclosures of this kind appear across Ireland in various forms, from ringforts used as farmsteads in the early medieval period to prehistoric ceremonial sites, and the relationship between an outer boundary and a smaller internal structure can suggest anything from a defended homestead with a separate inner compound to a site that was reused or modified across different periods. Without excavation, the function and date of the Ardnehue enclosures remain open questions. A related enclosure sits approximately 330 metres to the west-southwest, raising the possibility that this part of Carlow once held a loose cluster of such features, their original connections long since erased by centuries of farming.