What was once a large oval enclosure, substantial enough to carry the label "Fort" on an early Ordnance Survey map, has been reduced to a low earthen scarp, between 0.3 and 0.7 metres in height, curving in a gentle arc from west-southwest around through north to north-northeast. The monument has been levelled, and the field has long since closed over whatever once stood or gathered here.

The 1837 edition of the Ordnance Survey six-inch map is one of the most detailed early records of the Irish landscape, produced during a period of systematic cartographic effort that captured thousands of earthworks, enclosures, and field features that were already ancient at the time of surveying. The designation "Fort" on such a map typically points to a ringfort or similar enclosed settlement, a class of monument built predominantly during the early medieval period, roughly between the fifth and twelfth centuries, and used as a farmstead or place of residence by a family or small community. They are among the most common archaeological monument types in Ireland, yet individually many have been lost to agriculture, drainage, and the slow erosion of centuries. At Lisbrack, the process of levelling has been thorough enough that only the faintest curvature of the original boundary remains legible in the ground.