It measures just under twenty-five metres across at its widest point, enclosed by an earthen bank that still stands to about 1.3 metres in height. In places that bank is faced with stone, a detail that lifts it slightly above the purely ordinary, and there is evidence of a fosse, a defensive ditch, that has long since silted up around it.

This is a rath, the most common type of early medieval settlement monument in Ireland. Raths were typically the enclosed farmsteads of free farming families, built roughly between the sixth and twelfth centuries, and several thousand survive across the country in varying states of preservation. The enclosing bank and fosse were less about military defence than about marking territory, keeping livestock in, and projecting a degree of social status. The Derryvahalla example retains a narrow entrance gap, just 0.65 metres wide, oriented to the north-north-west, which is somewhat unusual given that most rath entrances face east or south. Within the interior, cultivation ridges are visible in the north-east quadrant, the kind of lazy-bed or ridge-and-furrow earthworks associated with tillage activity, suggesting the enclosed space was worked as agricultural ground at some point, whether during the original occupation or in a later period of use.