No earthwork, no rise in the ground, no scatter of stone. The only evidence that something is there at all came from the air, when an aerial photograph taken in August 1996 captured a circular cropmark, the kind of ghostly outline that appears when buried features alter the rate at which crops above them grow or ripen. Soil disturbed by ancient digging tends to retain moisture differently from undisturbed ground, and in dry summers especially, those differences can show up as distinct rings or lines visible only from above.

Cropmark enclosures of this kind are generally understood to represent the remains of a rath or ringfort, the enclosed farmsteads that were built across Ireland in their thousands during the early medieval period, roughly between the fifth and twelfth centuries. They were typically defined by a circular bank and ditch, enclosing a domestic space used for habitation and the sheltering of livestock. Over centuries of cultivation, the upstanding elements can be completely levelled, leaving only the filled-in ditch as a buried anomaly. At Nicholastown, that anomaly survives as a cropmark on a single aerial photograph, on a gentle slope just off the crest of a hill, with a second enclosure recorded approximately one hundred metres to the south-west. The proximity of the two sites is not unusual; paired or clustered enclosures appear regularly across the Irish midlands and south, sometimes suggesting family groupings or successive occupation of the same general area.