Look closer and the geometry becomes clear: a roughly circular enclosure, about forty metres across, defined by an earthen bank that still stands to around one and a half metres in height along its western and southern arc.

This is a rath, the Irish term for the type of ringfort built from earth rather than stone, and one of thousands scattered across Ireland that date broadly to the early medieval period, roughly the fifth to the twelfth centuries. They functioned primarily as farmsteads, the enclosing bank offering a degree of protection for a family, their livestock, and their stores. At Lurriga, the bank does not complete the full circuit under its own effort. To the south, a natural rock outcrop steps in to form a scarp, doing the work the builders might otherwise have had to do by hand. Three gaps interrupt the bank: one to the east at six and a half metres wide, one to the south-east at seven and a half metres, and a narrower break of two metres to the north-west. The eastern and south-eastern openings are wide enough to suggest they may have served as original entrances rather than later disturbances, though certainty is difficult after so many centuries of agricultural use.

The drumlin setting is itself worth noting. Drumlins are the smooth, elongated hills left by retreating glaciers, common across parts of Munster and Ulster, and their slightly elevated, well-drained summits made sensible locations for settlement. The stream running to the north would have supplied water close at hand. Today the interior, like the bank, is colonised by ferns, which have a habit of thriving in the undisturbed soil of sites like this, where the plough has never broken the ground.