The enclosure measures roughly 34 metres from east to west and just under 32 metres north to south, making it a substantial feature even if its low profile does not demand attention. An earthen bank, between 2.2 and 5 metres wide, runs around most of its circumference from the south-west, around the north, and back to the south-east. On the interior that bank rises about a metre above the enclosed ground level; on the exterior, between 1.2 and 1.8 metres. A fosse, the shallow external ditch that typically accompanied such banks as part of a unified boundary system, is still faintly traceable at the south-east and west, though it has silted and settled to a depth of only around 0.3 metres.

Enclosures of this kind are among the most common yet least understood monument types in the Irish archaeological record. They are generally grouped under the broad category of ringworks or embanked enclosures, a loose classification that can cover everything from early medieval farmsteads to enclosures of uncertain ritual or communal function. The defining feature is the earthen bank, sometimes accompanied by a fosse, enclosing a more or less circular area. At Gaynestown, one detail is particularly telling: the original entrance can no longer be identified. Either time and agricultural activity have obscured it, or it was never obvious to begin with. Without knowing where people went in and out, it becomes harder to say how the space was used, or by whom, or when.