It sits in ordinary pasture, its earthen banks colonised by thorn and briars on the western and northern sides, its interior a rough patch of grass and thistles. What makes it quietly remarkable is the precision of its survival: the outer bank still stands to around 1.8 metres above the surrounding ground, and the inner face rises to roughly 1.5 metres, enough to give any visitor standing at the centre a distinct sense of being inside something deliberately made.

This is a rath, the Irish term for a ringfort, the most common type of early medieval settlement monument found across Ireland. Typically dating from roughly the sixth to the tenth century, raths were enclosed farmsteads rather than fortifications in any military sense: the earthen banks, often accompanied by an external fosse or ditch, defined a household space, keeping livestock in and wolves or rival neighbours out. The Knockardnacorlan example is roughly circular, measuring 34.8 metres north to south and 33.7 metres east to west, with an external fosse running around much of its circumference. A slight dip in the bank on the south-south-east side, around four metres wide, is the probable original entrance, oriented to face down the slope toward the lower ground. The site was recorded and compiled by Denis Power, with notes uploaded in August 2011.

Access is across private farmland, so permission from the landowner should be sought before visiting. The rath sits immediately below the ridge brow, meaning it is not visible from any great distance; approaching on foot from lower ground to the south-east gives the clearest sense of the earthworks as a coherent whole. The interior is level, which is typical of sites in this condition, and the best-preserved stretch of internal bank runs from the south-west around to the east. The fosse is shallow, only around 0.2 metres deep in places, so the drama of the site is less in its ditch and more in the way the encircling banks still hold their shape after more than a thousand years of agricultural use around them.