The rath at Gortalassa was already described as "remarkably large" when it was recorded in the 1840s, and the Ordnance Survey Name Books noted even then that the townland itself derived its name from the enclosure. That the place is named after the fort, rather than the other way around, suggests the structure once made enough of an impression on the landscape to serve as a landmark for the whole surrounding area.

A ringfort, or rath, is an enclosed circular farmstead of early medieval Ireland, typically defined by one or more earthen banks and used as a defended homestead. At Gortalassa the bank survives in arcs along the west, northwest, north, and south-south-east of the enclosure, describing a roughly circular interior measuring approximately 34 metres across. The bank itself, around 6 metres wide, now barely rises above the ground inside, though it still stands to about 0.4 metres on its outer face. What the 1846 Ordnance Survey map recorded as an oval area of roughly 60 metres east to west and 50 metres north to south had, by the 1897 edition, already been truncated by field boundaries cutting across the north-east and south-west. Those same boundaries have continued their work, and the fort has been largely levelled. A single stone set just inside the bank to the west-north-west may mark the entrance to a souterrain, an underground passage or storage chamber of the kind commonly associated with ringforts. The souterrain has not been excavated, and the stone sits quietly in the grass, its purpose unconfirmed.