The site at Ballynisky is a circular enclosure roughly twenty metres in diameter, visible not as upstanding stonework or earthwork but as a crop mark, the kind of subtle discolouration in growing vegetation that betrays buried features beneath the soil. Crop marks form when underground remains, such as filled ditches or collapsed walls, affect how plants above them grow and colour; from ground level you would likely see nothing unusual at all.

The enclosure came to light not through excavation or fieldwork but through aerial photography. Images taken by the Aerial Survey of Ireland Archaeological Project in March 2006 captured the circular mark on a south-east facing slope in pasture, sitting roughly forty metres south of a stream that forms the townland boundary between Ballynisky and Lissatotan. The site had never appeared on Ordnance Survey maps, meaning it had slipped through the conventional record entirely until that flyover. A separate enclosure, recorded as LI019-205, lies about 140 metres to the north-east, suggesting this part of Limerick may have seen more settlement activity than the mapped record alone would indicate. The site was subsequently confirmed visible on a Google Earth orthoimage captured in April 2015, and the record was compiled by Martin Fitzpatrick and uploaded in July 2020.

There is nothing to see on the ground in the conventional sense. The land is private pasture, and the circular feature is only legible from the air or through the aerial imagery now held in the record. For anyone curious enough to look, the Google Earth image from 2015 offers the clearest view of the crop mark in its landscape context, set against the stream and the gentle slope of the surrounding fields. The value here is less in visiting than in understanding how much of Ireland's early settlement pattern remains invisible until the right season, the right crop, and the right angle of light conspire to briefly give it away.