Somewhere in the fields around Harristown in County Kildare, the outline of a large circular enclosure lies buried beneath the soil, invisible to anyone standing at ground level, yet legible from above as a ghostly pattern in the grass. The site belongs to a category of monument known from aerial photography alone, where buried ditches and banks cause the crops above them to grow at different rates, producing colour and height variations that become visible during dry summers. These patterns, known as cropmarks, can betray the presence of structures that have left no trace whatsoever on the surface.

The enclosure at Harristown is a multivallate one, meaning it was originally defined by multiple concentric ditches or banks rather than a single boundary. Its diameter runs to approximately 150 metres, placing it firmly in the larger end of the scale for such monuments. Enclosures of this kind in Ireland range in date and function across a wide span, from prehistoric ceremonial sites to early medieval ringforts, and without excavation it is not possible to say with any confidence what purpose this one served or when it was constructed. The cropmark was identified in aerial imagery captured on 28 June 2018, a summer date that would have favoured exactly the kind of dry soil conditions under which such features become visible from the air.