It is not much to look at now: an L-shaped stub of stone, roughly two and a half metres wide and barely thirty centimetres high, tracing out a footprint approximately ten metres east to west and six metres north to south. The date is genuinely unknown. What survives is enough to suggest a structure, but not enough to say with confidence when it was built, who lived there, or for how long.

A cashel is a type of early Irish stone-walled enclosure, broadly comparable in function to an earthen ringfort, and typically associated with early medieval settlement, though they were built and reused across a long span of time. The presence of a possible house site within the eastern interior of the cashel at Mannin fits a pattern seen elsewhere in Ireland, where the sheltered interior of such enclosures was used for domestic as well as defensive purposes. The outer cashel at Mannin carries its own separate record, and the house traces were identified as a distinct feature within it. Beyond the dimensions and the L-shaped plan, the archaeological record at this site is sparse, which is itself informative: the walling has survived only just, and any original floor surface, roof structure, or domestic material would long since have disappeared or remain unexcavated.