Built by the prominent Mac Uilliam Íochtarach (Lower MacWilliam) family, who controlled much of what is now County Mayo, the castle served as both a defensive stronghold and a symbol of their considerable power in Connacht. The structure follows the typical design of Irish tower houses from this period, with thick limestone walls, narrow windows, and a rectangular footprint that maximises both living space and defensive capability.

The castle’s strategic location wasn’t chosen by accident; it overlooks the tidal estuary of the River Moy and sits close to the ruins of Moyne Abbey, a Franciscan friary founded in the 1450s. This proximity to both religious and maritime routes made it an important seat of power for the Mac Uilliam Íochtarach, who needed to maintain control over trade, fishing rights, and the movement of people through their territory. The tower house features a distinctive Scottish-style corbelled roof, unusual for Irish castles of this period, which suggests possible architectural influences from Scotland or the employment of Scottish masons in its construction.

Today, visitors can explore the castle’s multiple floors via a narrow spiral staircase, though care is needed as the structure is largely unrestored. Each level reveals different aspects of medieval life: the ground floor likely housed storage and livestock; the middle floors contained the main hall and private chambers; whilst the top floor provided defensive positions and panoramic views across the surrounding countryside. The castle remained occupied into the 17th century but was abandoned following the Cromwellian conquest of Ireland, after which it fell into gradual ruin, leaving behind the impressive stone shell that still dominates the local landscape.