Its existence became known only through aerial photography, where the buried remains of a surrounding ditch, or fosse, left a faint circular shadow in the growing crops above it. This phenomenon, known as a cropmark, occurs when soil disturbed by past human activity retains moisture differently from undisturbed ground, causing the vegetation overhead to ripen or stress at slightly different rates. From the air, on the right day in the right season, those differences become legible as geometry. The enclosure at Furzehouse measures approximately 35 metres in diameter, which places it broadly within the range of the ringfort tradition, though without excavation it is difficult to say precisely what it was or when it was built.

What makes the site particularly interesting is that it is not alone. A second, smaller enclosure is also visible as a cropmark nearby, and it appears to overlie the south-western quadrant of the larger one. Overlying, in this context, is significant: it suggests the smaller feature was constructed after the larger one had already gone out of use, or at least after the original boundary had ceased to matter. The two enclosures were identified together from aerial photographs taken on 22 July 2000, a summer date well suited to the kind of dry conditions that make cropmarks most visible. The stratigraphic relationship between the two, one cutting across the edge of the other, implies at least two distinct phases of activity in this corner of the Kilkenny landscape, with an unknown interval between them.