Around the local church and graveyard, a large curvilinear enclosure roughly eighty metres in diameter lies almost entirely invisible at ground level, its presence betrayed only by a cropmark, the phenomenon where buried ditches and banks alter the growth rate of crops above them, producing faint colour and height differences that become legible from the air.

The enclosure was recorded from an aerial photograph taken on 22 July 1989, which shows the cropmark of a fosse, essentially a broad defensive or boundary ditch, tracing a curved line around the ecclesiastical site. This kind of enclosure is a well-recognised feature of early Irish Christianity; monasteries and church settlements were routinely enclosed within circular or oval boundaries, the circuit marking both a practical perimeter and a sacred threshold. The ditch at Holdenstown surrounds the existing church and graveyard, suggesting the enclosed area preserves the footprint of an early medieval religious foundation, its original boundary long since ploughed or worn flat. The feature remained visible in satellite imagery as recently as September 2019, confirming it is not a fleeting or ambiguous mark but a persistent trace of something substantial that once stood here.