Others exist only as faint discolourations in a crop of barley, visible for a few weeks in a dry summer when the soil's buried secrets show through the green. The enclosure at Oldtown, County Kilkenny, belongs firmly to the second category. What is known of it comes almost entirely from a single aerial photograph taken on 13 July 1989, which caught the cropmark of a roughly circular enclosure, approximately 50 metres in diameter, pressed into the tillage fields near the River Nore.

Cropmarks form when buried features, ditches, walls, or pits, affect the growth of crops above them. A filled-in ditch retains more moisture than the surrounding soil, producing a lusher, darker strip of growth; a buried wall does the opposite. Seen from the air in the right conditions, these variations sketch out the ghost of a former structure with surprising clarity. In this case, the photograph revealed not only the circular outline of a fosse, the term used for a defensive or enclosing ditch, but also a distinct entrance gap facing westward, oriented directly towards the River Nore lying some 250 metres away. That deliberate alignment suggests the enclosure's occupants had a considered relationship with the river, whether for water, transport, or simple proximity. A field boundary that once ran roughly east to west along the northern edge of the site has since been removed, so even that modest landscape context has been lost.