This impressive earthwork consists of a raised trapezoidal platform, measuring roughly 28 metres north to south and 22.5 metres east to west, surrounded by a complex system of earthen banks and water-filled ditches. The site’s most distinctive feature is its triple-bank construction; two complete circular banks with intervening fosses encircle the entire structure, whilst a third flat-topped bank appears only on the southern side, suggesting either incomplete construction or a specific defensive purpose.

The inner bank stands about 2.8 metres wide with modest interior heights of 30 centimetres, rising to 90 centimetres on the exterior face. The middle bank, broader at 3.9 metres and distinctly flat-topped, provides an intermediate defensive layer before the outer fortifications. Access to the interior was controlled through a single entrance on the western side, approximately 2.9 metres wide, which would have originally featured some form of bridge or causeway across the water-filled ditches. The level, grass-covered interior would have once hosted timber buildings, likely including a hall house and various outbuildings typical of Anglo-Norman settlements in medieval Ireland.

Aerial photography has revealed two possible leats extending westward from the inner fosse on the southern side, suggesting a sophisticated water management system that kept the defensive ditches filled whilst potentially providing drainage for the inhabited platform. These moated sites, introduced to Ireland by Anglo-Norman settlers in the 12th and 13th centuries, served as fortified farmsteads for wealthy landowners, combining defensive capabilities with agricultural management. The Lissananny Beg example, recorded in detail during the Archaeological Inventory of County Sligo survey, represents one of the better-preserved examples of these distinctive medieval monuments in the region.