The designation is spare, almost cautious, but it points to something genuinely difficult to categorise. The enclosure is roughly ten metres across, ringed by a waterlogged fosse, which is essentially a wide ditched depression, and an outer bank of earth and stone. That bank survives to only about forty centimetres in external height, modest enough, but its width of five metres suggests something that was once more substantial. A gap of five metres in the bank faces to the southeast, the kind of deliberate opening that recurs in ceremonial enclosures across Ireland and tends to indicate an intended approach or alignment rather than simple deterioration.

The broader landscape setting adds to the quiet strangeness of the place. Higher ground in County Wicklow lies a couple of kilometres to the northwest, and a slight hill rises about eight hundred metres to the east, so the site sits in a natural hollow, gathered in by the terrain on multiple sides. A pond lies approximately thirty metres to the northeast and is recorded as a separate but associated feature, which raises the possibility that water, or the management of it, was bound up with whatever this enclosure once meant. Ritual use of watery or liminal places, the kinds of spots where water gathers and land becomes uncertain, has deep roots in Irish prehistoric and early medieval practice, though the precise date and function of the Knockbrandon enclosure are not recorded. The whole complex now sits within a coniferous plantation, which has both preserved and obscured it.