It measures approximately 50 metres east to west and 37 metres north to south, its outline still legible as a scarp, the slight drop in ground level where an enclosure edge once stood, backed by an external fosse, a shallow defensive ditch running around the perimeter. What makes it particularly curious is a possible rectangular annexe projecting from its north-north-east side, a feature that complicates any straightforward reading of the site and raises questions about how it was used and by whom.

Ringforts, the most common monument type surviving in the Irish landscape, were typically circular or near-circular enclosures used as farmsteads during the early medieval period, roughly the fifth to twelfth centuries. This example at Lackan sits in grassland and is not alone in its immediate surroundings. A second ringfort lies only 140 metres to the north-east, and Kilfaughny Castle stands around 350 metres to the west-south-west, a proximity that suggests this corner of Westmeath accumulated significance across several different periods. The oval plan and the annexe here are subtle departures from the standard form, and the details of the site's outline were picked out not by excavation but from aerial photography, the kind of analysis that reveals cropmarks and earthwork shadows invisible at ground level.