Built in the late medieval period, this fortified tower house served as the stronghold of local Gaelic lords who controlled this strategic position overlooking the surrounding countryside. The castle’s thick walls and narrow windows speak to an era when defence was paramount; families needed protection not only from rival clans but also from the encroaching English forces that sought to extend their control westward from the Pale.

The castle’s most dramatic chapter came during the Cromwellian conquest of Ireland in the 1650s, when Oliver Cromwell’s forces systematically dismantled Irish Catholic power structures across the country. Like many fortifications of its kind, Castle Bellass likely suffered damage during this period, though local tradition suggests it remained partially inhabited well into the 18th century. The structure showcases typical features of Irish tower houses, including vaulted ceilings on the lower floors for fire protection, a spiral staircase built into the thickness of the walls, and murder holes above the entrance through which defenders could rain down projectiles on unwelcome visitors.

Today, the ruins offer visitors a glimpse into the lifestyle of Gaelic nobility, with remnants of domestic spaces still visible amongst the stonework. The castle’s position provides commanding views across the Mayo landscape, revealing why this location was chosen for such an important defensive structure. Archaeological evidence suggests the site may have been occupied even before the current castle was built, possibly serving as an earlier ringfort or ecclesiastical settlement, adding yet another layer to this compelling piece of Irish heritage.