What was recorded on the 1837 Ordnance Survey Fair Plan map as a broad circular fort has, over the intervening centuries, shifted in shape; it now presents as a slightly raised, sub-rectangular enclosure, roughly 24 metres north to south and 21 metres east to west. The bank and its shallow external fosse, a drainage or defensive ditch running around the outside of the enclosure, survive only along the southern and northwestern arc. At the southwest, a gap roughly 2.3 metres wide may mark the original entrance. The transformation from a neat circle to something more irregular is the kind of quiet distortion that centuries of farming quietly accomplish.

A ringfort, or rath, is a type of enclosed settlement common across early medieval Ireland, typically dating from roughly the sixth to the twelfth century, built as a farmstead or family enclosure rather than a military fortification in any modern sense. This particular example sits in unusually dense company. A motte and bailey, the earthwork castle form introduced by the Normans in the twelfth century, lies just 140 metres to the northeast. Taghmon church stands around 330 metres to the north-northwest, with a castle a little further off at roughly 460 metres in the same direction. The concentration suggests this hillside carried genuine strategic and community significance across several centuries. Aerial photographs taken in 1970 still showed the monument's outline clearly, even as field boundaries, including the townland lines separating Monkstown from Taghmon and Glebe, have since cut across the northern and northeastern perimeter. Inside the enclosure, faint traces of cultivation ridges run east to west, evidence that the interior was at some point ploughed, most likely long after any residential use had ended.