The site here is a rath, a type of circular earthwork enclosure used in early medieval Ireland, typically as a farmstead, defined by a bank and sometimes a ditch. This particular example is described as univallate, meaning it had a single enclosing bank rather than the double or triple rings found at more elaborate sites. That bank has largely disappeared, with only faint traces surviving along the north-east and east. What draws the eye now are five small mounds rising within the interior, three arranged in a rough line running north-west to south-east, the other two positioned towards the north-east and east sectors. Their purpose is unrecorded.

The real curiosity lies underground, or rather in what is no longer underground. A souterrain is a man-made subterranean passage or chamber, built in dry stone without mortar, and found across early medieval Irish settlements, most often interpreted as storage spaces or places of refuge. At Knockbrack, a landowner named Mr Collis reported that the visible entrance to the souterrain had been filled in some years before the site was surveyed. The details come from C. Toal's North Kerry Archaeological Survey, published in 1995, which recorded the rath and its underground component together. By that point the entrance was already gone, sealed up and inaccessible, leaving behind only the low earthen mounds and the much-disturbed circular platform to suggest what had once been a more complete and legible site.