This 16th-century tower house once stood as a formidable stronghold for local chieftains, built during a period when such fortifications dotted the Irish landscape. The castle's name derives from the Irish 'Sean na Gabhna', meaning 'John of the Smith', suggesting a connection to local craftsmanship or perhaps a notable figure in the area's history.

The castle remains consist primarily of a rectangular tower house, typical of the defensive structures built by Gaelic and Anglo-Norman families throughout this period. Its walls, though now partially collapsed, still reveal the careful stonework and defensive features that made these buildings both homes and fortresses. Arrow slits, narrow windows, and thick walls speak to an era when comfort took second place to security; the castle would have commanded views across the surrounding lands, allowing its occupants to spot approaching visitors or threats well in advance.

Today, the site offers visitors a glimpse into Mayo's turbulent past, when clan rivalries and English expansion shaped the political landscape. The ruins stand on private farmland, surrounded by the same fields that would have supplied the castle's inhabitants centuries ago. While time and weather have taken their toll on the structure, enough remains to appreciate the skill of its builders and imagine the lives of those who once called this remote corner of Mayo home.