Measuring roughly 47 metres north to south and 30 metres east to west, the enclosure is defined by a low earthen bank, the kind of feature that can be easy to walk past without recognising what it represents. What makes it quietly puzzling is what is absent: there is no visible fosse, the external ditch that typically accompanies such earthworks, and no identifiable original entrance survives. The perimeter has also been clipped by later field boundaries, an east-west bank cutting across the south side and a north-south bank trimming the west.

Structures of this type are broadly referred to as ringforts, earthen enclosures that were the dominant form of rural settlement in early medieval Ireland, typically dating from roughly the fifth to the twelfth century. They were used as farmsteads, their banks and ditches serving to define a household's space and protect livestock rather than to mount any serious military defence. The term "fort" attached to such sites by later generations overstates their martial character considerably. What survives at Lisdadanan is the bank itself, modest in scale, with a base width of around 4.7 metres at the northern arc and an internal height of roughly half a metre. The drumlin landscape of south Leitrim, shaped by glacial deposits into a series of elongated ridges, would have made such a slope a practical choice for settlement, offering drainage and a degree of natural elevation.