The site at Cluain Mhic Cáinín is a subrectangular enclosure, a type of monument defined by a boundary of raised earth and stone that once demarcated a space from its surroundings, whether for settlement, agriculture, or ritual purposes. What makes this particular example quietly curious is how little of it remains visible, and yet how much can still be read in the ground.

The enclosure measures roughly 30 metres east to west and 18 metres north to south. It was first identified during aerial reconnaissance in 1989, when the low banks became legible from above in a way they rarely are at ground level. The western, northern, and eastern sides survive as a bank of earth and stone about 2.2 metres wide, rising only around 18 centimetres on the interior and 30 centimetres on the exterior. The southern side is more heavily levelled, with a wider but flatter bank surviving at just 15 centimetres above the exterior ground surface. Short lengths of linear banking project outward from the north-east and south-east corners, and a separate linear bank, running roughly north to south for about 21 metres, is visible approximately 13 metres to the east. A large D-shaped depression encloses the area to the south, adding another layer of form to what is already a complex arrangement of earthworks. Some recent ground disturbance has affected the monument. Cloonacauneen Castle lies roughly 20 metres to the north-west, close enough that the two features almost certainly share a landscape history, though the precise nature of that relationship remains unresolved.