This is a rath, the most common type of early medieval enclosure in Ireland, built by farming families as a defended homestead, typically consisting of an earthen bank and an outer ditch enclosing a circular or oval living space. What the Lisduff example offers is a quietly legible version of that form, worn down by centuries of agriculture but still coherent in its outline.

The enclosure measures roughly 33 metres east to west and 26 metres north to south, its perimeter defined by an earthen scarp about 1.8 metres high on the outside and 1.8 metres wide. Beyond that bank runs a fosse, the defensive ditch that would originally have ringed the entire structure, here measuring 7.4 metres wide and half a metre deep. Notably, the fosse disappears along the north-western to south-western arc, either eroded away or never completed on that side. A later field boundary bank has been built directly on top of the scarped edge along the north-east to south-east stretch, a common fate for ringforts, which were often pressed into service as ready-made field divisions long after their original function was forgotten. The original entrance has not survived in any recognisable form, which is itself informative: entrances are usually the first feature to be obscured when a site is reused or gradually absorbed into agricultural land.