It is easy to miss: a slight change in the ground, a low scarped edge barely ten centimetres high, a shallow surrounding ditch half-swallowed by vegetation. Yet the geometry is deliberate and old, an oval roughly fifteen metres across from north-north-west to south-south-east and twenty metres from west-north-west to east-south-east, laid out with a purposefulness that suggests domestic or agricultural use stretching back centuries.

The enclosure was recorded by Denis Power and uploaded to the sites and monuments record in August 2011. It is defined by a scarped edge, essentially a cut or trimmed bank where the ground drops away, roughly two and a half metres wide. Beyond that edge lies an external fosse, the technical term for a ditch dug as a boundary or defensive feature, measuring around six and a half metres wide and thirty-five centimetres deep. There are two breaks in the circuit: a formal entrance approximately six metres wide at the south-south-east, and a narrower breach of about two metres at the north, which may be secondary or the result of later disturbance. Enclosures of this type in the Irish midlands and west are frequently associated with early medieval settlement, though without excavation the dating at Ballinvullin remains uncertain.

The most immediately visible feature today is botanical rather than archaeological. Yellow flag iris, iris pseudacorus, has colonised much of the fosse, its broad strap-like leaves and bright summer flowers marking the line of the ditch more clearly than the earthwork itself does. This makes late spring or early summer a useful time to visit, when the plants are at their tallest and the ditch line is most legible from a distance. The enclosure sits in private farmland, so access would require landowner permission. Those who do get a closer look should concentrate on the southern entrance, where the scarp is most intact, and take a moment to walk the perimeter, since the oval shape only becomes apparent once you have traced its full circuit on foot.