At around 53 metres across in both directions, it is not a small structure, yet it makes no dramatic claim on the landscape. The bank itself, between one and two metres wide and less than a metre high at its tallest, is faced with large rounded and irregular boulders, the kind of construction that speaks of considerable effort but has spent centuries slowly losing the argument with time and weather. Several sections have eroded away or collapsed entirely, with gaps at the north-east, east, south, south-west, and north-west, leaving what was once a complete circuit looking more like a broken necklace.

Enclosures of this type are a common feature of the Irish countryside, though their purposes varied considerably. Some served as ringforts, the enclosed farmsteads of the early medieval period, while others may have had an agricultural function at different periods altogether. What makes the Bookaun example particularly interesting is the complexity visible within it. The south-eastern quadrant of the interior is partitioned off by a further bank of earth and stone, now heavily degraded, creating a subrectangular sub-division roughly 19 metres by 22.5 metres. A large prostrate stone, at least 2.7 metres long and a metre wide, protrudes from the ground within this partitioned area; it may be bedrock pushing through the surface rather than a placed or worked stone. A gap of about three metres in the southern bank of the main enclosure provides direct access into this inner compartment, suggesting the division was always meant to be reached separately, or at least deliberately. Beyond the enclosure itself, a boulder field wall extends 18 metres southward from the south-western edge, and the traces of another boundary abut the southern side. These are fragments of a wider field system that once crossed the hill, only portions of which survive. Immediately to the north-west sits a mound, a separate monument, making this corner of Sligo a quietly layered place where different phases of human activity have left overlapping marks on the same ground, close to the Ballybeg River about a hundred metres to the east.