When the Archaeological Survey of Ireland inspected the site in 2000, their surveyors found no extant trace above ground level, only faint undulations in the pasture suggesting that something once stood there. And yet, in satellite imagery taken in June 2018 and again in February 2020, the outline of a fosse reappears, a ghostly circular impression measuring roughly 28 metres north to south and 32 metres east to west, made visible by differences in soil moisture or grass growth that no amount of agricultural activity has managed to erase.

A ringfort, sometimes called a rath, is one of the most common archaeological monument types in Ireland, typically a circular enclosure defined by an earthen bank and an outer ditch, or fosse, used as a farmstead during the early medieval period. This particular example in Ballylusky first appears in the documentary record on the 1840 edition of the Ordnance Survey Ireland six-inch map, where it is shown as a circular fort with an external diameter of approximately 30 metres. After that single appearance it drops out of the cartographic record entirely, not depicted on any subsequent mapping. The site sits on elevated pasture on a slight east-facing slope, with good views in all directions, a positioning typical of early medieval settlements whose occupants had practical reasons to monitor the surrounding landscape. Two further enclosures lie close by, one around 70 metres to the south-east and another roughly 125 metres to the south, suggesting that this corner of Limerick was once considerably more settled than its current agricultural character implies.

The site lies 175 metres north-east of the townland boundary with Rathbranagh, which gives a rough orientation when approaching across the fields. Because there is nothing visible at ground level in the conventional sense, a visit requires a certain patience and a willingness to read the land rather than look for obvious earthworks. The surface undulations noted by the ASI in 2000 remain the only physical clue on the ground itself. Overcast days after rain, when differences in grass colour and growth are more pronounced, offer the best chance of picking out the slight depression of the fosse. The satellite images compiled by Edmond O'Donovan and uploaded to the record in August 2020 are a useful reference before any visit, giving a clearer sense of the enclosure's shape than anything the eye alone is likely to catch standing in the field.