It is a ring barrow, a type of prehistoric funerary monument in which a low mound or flat central area is enclosed by a circular bank and ditch, and this particular example at Duncummin is modest even by the standards of its kind. The enclosed interior measures just four metres in diameter, bounded by a low earthen scarp no more than fifteen centimetres high and a shallow surrounding fosse, with traces of an outer bank still just visible.

What makes the setting at Duncummin quietly remarkable is not the barrow itself but the density of ancient features around it. A ringfort, the familiar circular enclosure once used as a farmstead in early medieval Ireland, sits only sixteen metres to the east. Another ring barrow lies twenty-four metres to the south-west, and further examples are recorded nearby. The barrow also sits on the north-western edge of a field system, and a drainage or boundary channel from that same system runs up to abut the outer bank of the monument at its south-south-west side, suggesting that later agricultural activity worked around, or at least up against, the older structure without entirely obliterating it. The interior remains level and clear of overgrowth, which gives the modest earthwork an unlikely air of preservation given how wet and active the surrounding ground appears to be.