What sits there is an oval rath, a type of enclosed farmstead used across early medieval Ireland, typically from around the fifth to the twelfth century, defined by earthen banks and ditches that once marked the boundary between a family's domestic space and the world beyond it. This example at Greenville is well-preserved, measuring roughly 57 metres north to south and 48 metres east to west, which puts it on the larger end of the scale for such monuments.

The enclosure is defined by an inner bank surviving most clearly at the northwest, with a scarp, a steep earthen slope serving the same boundary function, running around much of the remainder. At the western side, traces of both an intervening fosse, that is, a ditch, and an outer bank are still legible in the landscape, suggesting this was once a multivallate structure with concentric lines of earthwork defence or demarcation. A causeway at the west marks where the original entrance crossed the fosse, a feature that would have controlled movement in and out of the enclosure. The monument has not escaped entirely unscathed; quarrying has cut into the southeastern portion, removing material and disrupting the profile of the earthwork at that corner, a common fate for field monuments that sat adjacent to useful deposits of stone or gravel.