That detail, almost casual in its disregard for what came before, tells you a great deal about how these sites fade into the working landscape. The ringfort at Killeen sits on a low rise in rough, stony pasture, its roughly circular form measuring about 26.6 metres across. What defines it is an enclosing scarp, the steep inner face of an earthen bank, rising to around 1.5 metres on the northern and eastern sides, with a broader, more irregular stony bank completing the circuit to the south and west. Field clearance cairns, the piled stone gathered from centuries of working the surrounding ground, have been heaped against parts of the scarp, blurring its edges further.

Ringforts, known in Irish as raths when they are primarily earthen enclosures rather than stone-built cashels, are among the most common early medieval monument types in Ireland, typically associated with farming settlements of the sixth to tenth centuries. This one carries a particular feature that lifts it out of the ordinary: a souterrain in its south-western quadrant. A souterrain is an underground stone-lined passage or chamber, often built for storage or as a refuge, and their presence within ringforts is a strong indicator of early medieval occupation rather than later use. The fort's interior is uneven and stone-strewn, and a later field wall running roughly east to west bisects it almost centrally, having absorbed part of the original enclosing bank into its own structure on the western and northern sides. Immediately to the south-east lies a possible house site, suggesting the wider settlement extended beyond the fort's boundary.

The site is not formally managed or signposted, and the dense interior vegetation means that most of the structural detail is more legible from the margins than from within. The scarp is clearest on the north-east side, where the slope extends some 5.3 metres. The higher ground to the east-south-east gives a sense of the modest but deliberate positioning of the rath, placed for outlook across the surrounding pasture rather than for dramatic elevation.