A rath is a roughly circular enclosure, typically built during the early medieval period in Ireland, defined by one or more earthen banks and a fosse, which is the accompanying ditch dug to create them. What makes this particular example worth attention is the way natural topography and human construction have been woven together over centuries: where the ridge drops steeply to the north and east, the builders apparently judged the slope sufficient defence on its own, and so the outer bank simply fades away in those directions, leaving the landscape itself to do the work.

The rath measures approximately 34 metres along its northwest to southeast axis and retains two banks with an intervening fosse, all in fair condition. The inner bank survives continuously around the circuit, though along the northern and eastern arc a later field wall has been built directly on top of it, a common fate for ancient earthworks in agricultural landscapes where good stone or firm ground was not wasted. Two trackways cut across the monument, one at the west-northwest and one at the east-southeast, suggesting the site was worked around and through rather than carefully avoided as the surrounding land was farmed across the generations. A reference noted by Athy in 1914 and followed up by McCaffrey in 1952 points to a possible second enclosure lying immediately to the west, which, if confirmed, would suggest Rathshanbally was once part of a more complex arrangement of activity on this ridge rather than a single isolated feature.