A rough oval, roughly 26 metres east to west and 29 metres north to south, it is marked out by a single line of stones, most of them no bigger than 0.4 to 0.8 metres across and protruding only about 30 centimetres above the surrounding ground. For much of the circuit the stones are gapped, with breaks of one to three metres between them, so the ring reads less as a wall than as a dotted outline pressed into the heather. Only at the south-west does the line tighten, the stones sitting close together or touching. The interior is as wet and boggy underfoot as everything around it, with no raised platform to suggest a dwelling floor or any obvious sign of what the space was once meant to contain or exclude.

Enclosures of this kind, a broad category in Irish archaeology, range from the substantial raised ringforts of the early medieval period to far more ambiguous prehistoric boundaries whose original purpose is no longer readable. What makes Carrowculleen quietly puzzling is precisely that ambiguity. The stones are too slight and too intermittent to have kept anything securely in or out, and the interior offers no elevation above the surrounding bog. Several metres to the south-west and west of the enclosure, there are traces of what may be an associated field system, which hints that the monument once sat within a worked and bounded landscape, now largely swallowed by peat and heather. Whether enclosure and field system belong to the same period of activity is not established, but their proximity suggests this corner of Sligo was, at some point, a place where people were actively organising the ground beneath their feet.