It measures just 4.7 metres north to south and 3.75 metres east to west, which makes it roughly the footprint of a large garden shed. What it actually was, nobody can say with certainty.

The structure is built from roughly coursed limestone, meaning the stones are laid in approximate horizontal layers without the precision of dressed masonry. The east wall is the most complete section surviving, standing 1.8 metres high and between 1.3 and 1.5 metres thick, which is a substantial thickness suggesting something built to last, or built to impress, or both. The north wall has been partially rebuilt at some point, on a slightly different alignment to the original, while only the eastern end of the south wall remains and the west wall has disappeared entirely. The building sits 25 metres north of a tower house, the kind of tall, fortified stone residence that minor Gaelic and Anglo-Norman lords built across Ireland from the late medieval period onwards, and is also associated with a medieval church in the same cluster of monuments at Mellisson. That company is what gives the ruin its most plausible interpretation: the walling style and the grouping with the tower house and church together suggest a medieval date, though no more precise attribution has been established. It may have served a domestic, agricultural, or ecclesiastical function within whatever small settlement or estate once operated here, on this exposed and panoramic hillside looking out across a wide sweep of landscape from west through north to east.