The earthwork on the summit of a hill in Carrowmunniagh, County Galway, has been known in the area as the Great Fort for at least a century, a name recorded by Neary in 1914, even though the structure itself has been considerably reduced by quarrying. What remains is a subcircular rath, a type of enclosed farmstead typical of early medieval Ireland, measuring roughly 38 metres on its north-south axis. Its defining features, an inner scarp, an intervening fosse or ditch, and an outer bank, are only partially legible now. The scarp survives along the northern arc and from the east around through the south to the south-southwest, but elsewhere it has been cut away, and a field bank overlies the outer bank for much of its circuit. A scatter of small hollows punctuates the interior, the kind of depressions that often suggest later digging or structural disturbance.

Raths of this kind were built in their thousands across Ireland during the early medieval period, typically serving as the enclosed homesteads of farming families, their earthen banks defining both a practical boundary and a statement of status. What makes this particular example quietly interesting is the additional feature adjoining it to the east: a rectangular enclosure, roughly 21 metres by 17 metres, defined by an earthen bank of its own. This secondary enclosure is considered a possibly later addition, its straight-sided geometry sitting at an angle to the older, rounded form of the rath itself. Whether it served as an annexe, a livestock pound, or something else entirely is not recorded, but its presence complicates what might otherwise be read as a straightforward, if damaged, monument.