There are two breaks in the enclosing bank, one to the south measuring roughly 3.5 metres across, and another to the northwest at about 4 metres wide. Either could be the original entrance, and nobody, at least on current evidence, is prepared to say which.

The site is a rath, the Irish term for a ringfort, the kind of roughly circular enclosure built from earth and used as a defended farmstead during the early medieval period, broadly between the fifth and twelfth centuries. This particular example is nearly circular, measuring 26.5 metres both north to south and east to west. The earthen bank that defines it is still substantial in places, rising to about 2.1 metres on the exterior, though it has been worn down to a mere scarp along the eastern arc, where the ground slopes away and the edge has been slightly straightened over time. Outside the bank there is a fosse, a defensive ditch, around 4.7 metres wide, though it has been cut through by a field boundary on one side and by quarrying activity to the west-northwest. There is also a possible outer bank on the northwest to north-northwest arc, which if genuine would suggest the site once had a more elaborate defensive arrangement than its present condition implies. About 330 metres to the south-southwest lie a possible motte, the earthen mound associated with early Norman fortification, and the remains of a church and graveyard, suggesting that this part of Rosegreen accumulated layers of settlement and use across several centuries, each generation leaving its own mark on the same quiet slope.