The structure is a subcircular enclosure, roughly 27.5 metres east to west and 24 metres north to south, its boundary now reduced to a degraded bank that blends easily into the surrounding ground. A modern drainage channel cuts across its northeastern and east-southeastern edges, quietly erasing what centuries of weather had already begun to obscure. At its southern side, a small rectangular annexe, approximately 8.5 metres by 7 metres, extends outward from the bank, a detail that sets this site apart from a simple ring and hints at a more considered original layout.

Enclosures of this broad type are among the most common, and most debated, features of the Irish rural landscape. They range in date from the Iron Age through to the early medieval period and served a variety of purposes, from farmstead enclosures protecting livestock and households to more ceremonial or boundary-marking functions. The subcircular form here is characteristic of the kind of enclosed settlement that would once have sheltered a small farming community, with the annexe possibly serving as a separated yard or stock pen, a practical extension of the domestic space within the main ring. Without excavation, the precise date and function of the Tristaun example remain open questions, as they do for hundreds of similar earthworks scattered across Connacht.