It is roughly forty metres across, and the difference in height between its interior bank face and its exterior gives some sense of the original effort: the inside stands only about a quarter of a metre above the enclosed ground, while the outer face rises to around one and a half metres. What was once a deliberate boundary is now a green tangle, with the external fosse, a defensive ditch dug to accompany the bank, equally overgrown.

This is a rath, the Irish term for a ringfort, the most common type of early medieval monument in the country. Raths were typically the enclosed farmsteads of prosperous farming families, built roughly between the fifth and twelfth centuries. The earthen bank and fosse combination was not military fortification in any serious sense but rather a marker of status, a boundary against livestock straying, and perhaps a psychological perimeter against the world beyond. Thousands once dotted the Irish countryside; a great many have been ploughed out, built over, or simply eroded into invisibility. The Lisduggan example survives in the land because it occupies a slope that, while under tillage, has not been completely levelled. Its position overlooking the Blackwater valley suggests the people who built and lived within it chose the spot with some care, with good aspect, reasonable drainage on a south-facing incline, and a clear view down toward one of Munster's major river corridors.