That combination alone makes Lisnanore Fort an oddity worth pausing over. Drumlins, the smooth elongated hills that ripple across Ulster's landscape, were often chosen as sites for early enclosures precisely because their elevation offered visibility and a degree of natural defence. Here, whoever built or later adapted the fort seems to have found a secondary use for the high ground, erecting a windmill where once the logic was martial or territorial.

The enclosure itself is substantial: a roughly circular grass-covered area measuring around 73 metres east to west and 68.5 metres north to south, defined by a scarp, a steep earthen slope, with stone-facing at its base creating a narrow level berm, a flat ledge, running from the west around to the south-east. Beyond that lies an outer fosse, essentially a ditch, nearly four metres wide at the top and over a metre deep, which appears to have been pressed into service as a track along the northern and south-eastern edges. A wide entrance, nearly ten metres across, opens at the south-east. Beech trees line the top of the scarp, with oak trees planted inside them, and the whole composition was already well established by the time the first Ordnance Survey six-inch map was drawn in 1834, which depicts a large wooded enclosure on the site. By the 1907 edition it was marked as 'Lisnanore Fort' in the gothic lettering cartographers traditionally reserved for antiquities. The fort sits within the demesne of Bessmount House, about 800 metres to the south-west, suggesting that at some point the enclosure was absorbed into a landed estate and perhaps landscaped or embellished accordingly. A comparable large enclosure exists at Eden Island, roughly 700 metres to the west, hinting that the two sites may share some relationship, though what that relationship was remains unclear.