Exactly what stood here is now a matter of cartographic memory rather than physical evidence: by the time anyone came to look for it in 1998, the enclosure had left no trace visible above ground.

What we know comes largely from the 1840 edition of the Ordnance Survey six-inch map, which marks the outline of a rectangular enclosure at Knocknagroagh using hachures, the fine radiating lines surveyors used to indicate earthen banks and raised boundaries. By 1996 it had been formally catalogued as a rectangular enclosure, a category that covers a wide range of enclosed spaces, from farmsteads to small defended settlements, typically defined by banks, ditches, or walls. The Ballyvaughan valley is not short of such sites. Two cashels, which are stone-walled circular enclosures of early medieval origin, sit within roughly 120 metres of this spot, one to the east and one to the northwest. The rectangular enclosure at Knocknagroagh may have been broadly contemporary with these neighbours, or it may have served an entirely different function at a different period. Without surviving fabric, it is difficult to say more. The improved pasture that now covers the site, land that has been drained, fertilised, and heavily grazed over the agricultural improvements of the nineteenth and twentieth centuries, is the most likely explanation for the disappearance of whatever banks or ditches once defined this place.