It is a ring-barrow, a type of prehistoric funerary monument in which a central raised mound is encircled by a fosse, or ditch, rather than the outer bank more commonly associated with later ringforts. The Lisdoony example stretches to roughly 27 metres in diameter at its widest, with the domed central area rising between 1.2 and 1.6 metres above the surrounding ground. That central platform measures approximately 17 metres across, and the fosse around it, now heavily overgrown with rushes, varies noticeably in width: around 3 metres on the southern and south-western arc, widening to 7 metres along the north-western to north-eastern stretch.

The monument was already being recorded by the time the Ordnance Survey produced its 25-inch plan in 1897, marked again on the revised 6-inch edition of 1920, though it was somewhat unhelpfully catalogued simply as an 'Enclosure' in the Record of Monuments and Places as late as 1996. That misclassification is not unusual; ring-barrows, which belong broadly to the Bronze Age tradition of burial mounding, can be difficult to distinguish from the remains of later settlement enclosures when vegetation and field activity have done their work over centuries. At Lisdoony, modern drainage and field banks have cut into the mound at the south, west, north, and east, truncating what survives and making the full original form harder to read on the ground. Roughly 123 metres to the west-south-west, a rath, the circular earthen enclosure associated with early medieval farmsteads, sits in the same landscape, a reminder that this ridge was returned to, settled, and reshaped across very different periods of Irish history.

The site commands wide views in all directions from its ridge-top position, which was almost certainly part of its original significance, whether as a landmark, a territorial marker, or simply as a place where the dead were laid close to the sky. The rushes filling the fosse are the most reliable guide to its outline when approaching from the south or north-west, where the ditch remains most legible.