From a distance it might read as a natural undulation in the ground, but the geometry gives it away: a near-perfect circle, roughly 47 metres north to south and 46 metres east to west, enclosed by an earthen bank still standing around one and a half metres high. On the eastern and western sides, a shallow external fosse, the term for the ditch that typically runs alongside such an enclosure, traces the outer edge of the bank. Gaps on the south-east and south suggest original entranceways, or simply centuries of agricultural erosion and movement of livestock.

Ringforts of this type, formed from banked earth rather than stone, are among the most common surviving field monuments in Ireland, and most are thought to date from the early medieval period, roughly the fifth to the twelfth centuries. They functioned primarily as enclosed farmsteads, the bank and fosse offering a degree of protection for people and animals rather than serving any strictly military purpose. What makes Ballinlassa worth attention is its relatively well-preserved condition given its setting in working pasture, and the clarity with which the overall plan can still be read on the ground. The site sits on a slight rise, which would have been a deliberate choice by whoever laid it out, offering both drainage and visibility across the surrounding landscape.