The enclosing bank still stands to an external height of 3.4 metres, which is substantial for an earthwork that has been sitting in agricultural land for well over a thousand years, subject to the slow attrition of ploughing, grazing, and casual stone-robbing that has levelled so many of its counterparts.

A ringfort, or rath, is essentially a circular enclosure defined by one or more earthen banks and ditches, used during the early medieval period in Ireland as a farmstead and sometimes as a place of status. The example at Acres follows the standard principle: a roughly circular area, approximately 29 metres across in either direction, enclosed by a well-defined bank that varies in width from 3 to 7 metres at its base and retains a height of around 2.4 metres when measured from the interior. Around the outside runs a fosse, which is simply a ditch cut to deepen the effective height of the bank above it. Here, the fosse does not run the full circuit; it is best preserved on the southern and western sides, where it is flat-bottomed, around 4 metres wide and 1 metre below the level of the surrounding ground. That incompleteness is not unusual, but the preservation of what remains is. The site sits in gently northward-sloping pastureland and commands a clear view of the surrounding countryside, which would have been a practical consideration for whoever built it, since visibility over the land you farmed and defended was part of the point.