In a field in County Kildare, a long-vanished enclosure has left its outline pressed into the earth, legible only from the air and only under the right conditions. What survives is a cropmark, the kind of ghostly impression that appears in aerial photography when buried earthworks affect how crops or grass grow above them. Drier summers can cause the vegetation over compacted ditches and banks to yellow or green at different rates than the surrounding field, throwing ancient boundaries into sudden relief. In this case, the outline that emerged is circular and double-walled, the signature of a bivallate ringfort, a type of enclosed settlement that was widespread in early medieval Ireland, typically consisting of a central living area ringed by one or more banks and ditches.

The enclosure at Oldtowndonore has an interior diameter of roughly 26 metres and an overall external diameter of approximately 48 metres, suggesting a substantial double-ditched structure. The cropmark became visible in a Digital Globe aerial photograph taken on 28 June 2018, and was brought to wider attention by Anthony Murphy, whose observation formed the basis of the record. The site had apparently left no obvious surface trace, which makes the aerial image the sole evidence for its existence and shape.