The mound is roughly eighteen and a half metres across, enclosed by a bank that still rises to about one and a half metres, and what makes it structurally unusual is the wet fosse, a waterlogged ditch, that runs not outside the bank as one might expect, but inside it, encircling a low central platform at the heart of the monument.

Ring barrows are prehistoric funerary monuments, typically Bronze Age in origin, consisting of a circular bank, sometimes with an associated ditch, built to enclose a burial or mark a place of ritual significance. They are found across Ireland and Britain, though the internal positioning of the fosse at Ballyleigh gives it a somewhat distinctive character. The detail comes from a 1939 observation by Hartnett, who recorded the wet fosse and central platform when the interior was presumably more accessible than it is today. That description, now several decades old, remains the primary close-up account of what lies within the bank.