What was once a rath, an enclosed farmstead of the early medieval period typically consisting of a raised bank and surrounding ditch, now survives only partially, its original form legible in places and entirely gone in others.

The site is roughly 55 metres in diameter. Along the arc running from the south-west through west to north, the original bank and its external fosse, the ditch dug to throw up that bank, remain visible. But from the north around through the east and back to the south-west, the bank has been levelled, leaving only what is described as a degraded scarp, a slight slope in the ground where the earthwork once stood. The effect is of a circle interrupted, present on one side and absent on the other, as though the landscape has been slowly reclaiming its own geometry.

Raths of this kind are among the most common archaeological monuments in Ireland, numbering in the tens of thousands, and they were the ordinary dwelling places of farming families across much of the first millennium and into the early medieval centuries. Their earthen banks were never fortifications in any serious military sense; they marked territory, sheltered livestock, and defined the household. The example at Knockaun carries no known historical associations and no particular drama, which is perhaps what makes its partial survival quietly telling. Agriculture, drainage work, or simple neglect has removed more than half of what was there, and what remains is modest enough to pass unnoticed in a field.