Almost nothing stands above ground level except a single gable wall at the southern end, pierced by two plain rectangular windows, which gives the site a quietly spectral quality, a fragment of vertical masonry presiding over a rectangle of near-invisible ground.

The structure measures roughly 14 metres north to south and 6 metres east to west, and within its outline there are traces of a mill race, the channel cut to direct water from the river onto a wheel, though this is now choked with rubble cleared from surrounding fields over the years. The survival of the race, even in this degraded form, helps confirm the building's industrial purpose. According to research by Holland in 1988, this is possibly the site of the medieval mill that served the borough of Kilcolgan, a settlement with its own civic identity in the medieval period. Mills of this kind were vital economic infrastructure in medieval Ireland, grinding grain for the surrounding community and typically held under the control of a lord or ecclesiastical body, generating income through the compulsory tolls paid by those who brought their grain to be milled.