The structure is roughly twenty metres in diameter, enclosed by a dry-stone wall standing to about 1.6 metres in height. What sets it apart from the surrounding field boundaries is its form: circular rather than the rectilinear geometry of agricultural enclosures, and substantial enough to suggest a deliberate, purposeful construction rather than a casual accumulation of cleared stone.

Dry-stone enclosures of this kind are found across Ireland, and their age and function can be difficult to pin down without excavation. Circular enclosures, sometimes called cashels or ring forts when their origins are early medieval, were used variously as settlement enclosures, livestock enclosures, or places with ritual significance. The enclosure at Ballylin is abutted at its south-south-east, north, and north-east sides by dry-stone walls that form part of the surrounding field boundary system, which may mean the later agricultural landscape simply grew around it, incorporating its walls as convenient boundaries without disturbing the enclosure itself. This kind of absorption is common in the Irish countryside, where ancient structures often end up quietly stitched into more recent land management. The site was recorded by Denis Power and uploaded to the record in August 2011.

The enclosure sits in rough pasture, and the interior is currently inaccessible due to dense overgrowth. A visitor would find it easier to read the outer wall than to explore within. The limestone crag setting is worth noting, since the local geology would have made good building stone readily available and may partly explain why the wall survives as well as it apparently does. Those interested in the relationship between the enclosure and the field system around it should look at the junctions where the later boundaries meet the circular wall, as these points of contact sometimes reveal something about the sequence in which the landscape was built up over time.