The structure measures approximately 8.85 metres east to west and 5.8 metres north to south, with walls that tell the story of medieval Irish architecture despite their fragmentary state. The ground floor consisted of a single chamber topped by a rounded vault, though this has largely collapsed over the centuries. The most intact feature is a window on the western wall, showcasing the defensive architecture typical of Irish tower houses with its splayed embrasure, segmental arch, and narrow lintelled opening that would have allowed defenders to observe approaches whilst remaining protected.

The castle’s other architectural elements hint at its former functionality; windows likely occupied central positions in both the north and south walls, whilst the main entrance appears to have been positioned in the eastern wall, though all are now badly deteriorated. Three wall presses, or recessed storage areas, can still be identified; two in the north and south walls and one in the western wall, suggesting the practical needs of those who once inhabited this fortress. Above the ground floor, only partial walling survives to hint at what would have been upper chambers and battlements.

Local tradition, recorded by the Ordnance Survey in 1841, connects this castle to a fascinating piece of McCarthy family history. According to these accounts, Fieries Castle was one of three fortifications belonging to McCarthy brothers, the others being the castles at Cluain Maolain and Magh Laithimh. This familial connection speaks to the McCarthy clan’s significant influence in medieval Kerry, where they controlled vast territories and built numerous strongholds to maintain their power. Today, whilst nature slowly reclaims the stone walls, these ruins remain an evocative reminder of the strategic importance of this valley and the families who once called it home.