Walk the slight south-east-facing slope where it lies and nothing distinguishes it from the surrounding farmland. The site exists, in any practical sense, only from the air.

A ringfort, or rath, is one of the most common monument types in the Irish landscape, typically the enclosed homestead of an early medieval farming family, defined by one or more circular earthen banks and ditches. At Tomcool Big, what survives is the ghostly outline of a roughly circular enclosure approximately thirty metres in diameter, probably shaped by two fosse features, that is to say concentric ditches dug into the earth. This double-fosse arrangement suggests a site of some modest elaboration, though the enclosure has been so thoroughly levelled, or perhaps so gradually eroded across the centuries, that aerial photography is the only means by which its plan remains legible. The outline was recorded on a Cambridge University Committee for Aerial Photography image. Archaeological testing carried out around 2019, roughly a hundred metres to the east of the enclosure, produced no material that could be connected to it, leaving the site's history largely unread.