A circular platform roughly eight metres across sits within a waterlogged fosse, a rock-cut or dug ditch intended to keep the central area isolated, and is ringed by an outer bank of earth and stone. The whole arrangement stretches to about thirty-five metres at its widest, with a deliberate gap in the bank on the south-east side, the kind of formal entrance that suggests controlled access rather than casual use. Two further ponds flank the site at close range, one to the south-west and one to the north-east, and their proximity is almost certainly not coincidental.

The classification as a ritual site reflects a broader pattern recognised across Ireland, where circular enclosures associated with water, particularly at springs or river sources, are understood to have had ceremonial rather than purely practical functions. The precise period of use at Knockbrandon has not been established from the available record, but the morphology, a raised central area, a wet surrounding ditch, a low bank with a single entrance, is consistent with monument types spanning the prehistoric and early medieval periods. The site sits in a shallow basin with a low hill to the east and higher ground in the Wicklow hills to the north-west, a setting that places it at a kind of geographical threshold, just inside the Wexford boundary, drawing water that will travel east.