What is most immediately striking about it is the engineering logic embedded in its construction: the interior has been deliberately cut into the hillside on the northwest side and built up on the southeast, so that the ground within sits level regardless of the natural slope. The enclosing bank of earth and stone still stands to a maximum external height of around 1.45 metres, running from north-northwest around to the west, and two gaps break its circuit, one to the north-northeast at roughly five metres wide and a narrower one to the southeast at two metres.

This is a rath, the Irish term for a ringfort, the most common type of early medieval settlement monument in the country. Ringforts were typically the enclosed farmsteads of farming families, built roughly between the sixth and tenth centuries, though some are earlier or later. They range from modest single-banked enclosures to elaborate multivallate structures associated with higher-status occupants. The Barradaw example is a relatively modest single-bank type, roughly 24.5 metres east to west and 23 metres north to south, but the care taken to level the interior on a sloping site suggests the people who built it were attentive to comfort and practicality. The two entrance gaps, particularly the wider one to the north-northeast, would have oriented daily movement across the enclosure in ways that are now difficult to read without excavation.