That hummock, however, is the remnant of a large subcircular enclosure, roughly 100 metres across from east to west and about 80 metres from north to south, placing it firmly in the category of substantial prehistoric or early medieval earthworks. Enclosures of this scale were typically used as ringforts or settlement enclosures, defined by earthen banks and ditches that once created a clear boundary between the domestic interior and the wider landscape.

What survives at Killiane is fragmentary. A degraded earthen bank can still be traced along the northern and north-western arc, and a scarp, a steep natural or artificial slope used here as part of the enclosing boundary, runs from the south-west around to the north-west. The south-eastern sector of the interior has been absorbed into working farmland, with agricultural buildings now occupying the ground where the enclosing elements once stood. No trace of the boundary survives in that quarter. A trackway cutting across the monument from north-north-west to south further complicates the picture, slicing through the archaeology in a way that makes reading the original form more difficult. The cumulative effect of these intrusions is that the enclosure reads less as a monument than as a faint topographic suggestion, legible mainly to those who already know what to look for.