What was once a circular or roughly circular boundary, defined by two earthen banks with an intervening fosse, a defensive ditch running between them, has been reduced to a single six-metre stretch along its north-western arc. The southern half is gone entirely, replaced by an irregular scarp, the ragged scar left by extensive quarrying that ate through the monument over an unknown period of years.

Enclosures of this type are among the most common archaeological features in the Irish landscape, typically serving as enclosed farmsteads, ringforts, or ceremonial spaces in the early medieval period, though some may be considerably older. The double-bank-and-fosse arrangement suggests this was a reasonably substantial example, a form sometimes associated with higher-status settlements. The quarrying that destroyed most of it was not unusual; earthworks throughout Ireland were routinely broken up for road fill, field drainage, or building material, particularly during the eighteenth and nineteenth centuries. What survives at Lerhin is therefore less a monument in any conventional sense and more a document of how such monuments disappear. A short distance to the west, Lerhin Castle still stands, a reminder that this small patch of ground has carried successive layers of occupation and use across many centuries.