The O'Flahertys -- O Flaithbheartaigh in Irish -- were among Connacht's most formidable Gaelic lordly families. They controlled the castle site from around 1250, and by the time the tower house was built in 1490, their territory encompassed most of Iar Connacht, the vast region west of Galway city. Aughnanure is one of over 200 tower houses in County Galway, built by both Gaelic and Anglo-Norman landowning families during the late medieval period. Most now lie in ruins. What makes Aughnanure exceptional is its completeness: six storeys of the original tower survive, along with crenellations, machicolations, bartizans, and carved water-spouts. An unusual double bawn enclosure surrounds the tower, featuring a unique round watchtower, docks on the nearby Lough Corrib, and the ruins of a banqueting hall with relief carvings depicting grapes and vines.

The O'Flahertys' independence ended not through defeat in battle but through the oldest colonial strategy: divide and conquer. In 1572, Sir Edward Fitton, President of Connaught, captured Aughnanure and granted it to Murrough na dTuadh O Flaithbheartaigh -- Murrough of the Battleaxes -- a junior member of the clan who accepted the legal formalities of recognising the English Crown. By elevating a compliant relative over the senior chieftains, the English divided the family's power and fractured their control over their vast territories. The O'Flahertys lost control of the castle but regained it briefly "by stealth" during the rebellion of 1641, a phrase that suggests the family's reputation for fury was well earned.

During the Cromwellian siege of Galway in 1652, Aughnanure served as a supply line for the besieged city, controlled by the Earl of Clanrickard. When Galway surrendered, the castle was abandoned. The O'Flahertys eventually bought it back, only to lose it again through foreclosure when they defaulted on a mortgage to Lord St George. The castle's final chapter as a family property came in 1932, when Peadar O'Flaherty of Enniscorthy, County Wexford -- a distant relative of the original Aughnanure O'Flahertys -- purchased it. In 1952, recognising that the castle's archaeological, historical, and architectural significance would be best preserved by the state, he donated it to Ireland. Shortly after completing his gift, he died.

The castle stands near the shores of Lough Corrib, Ireland's second-largest lake, in a landscape that shifts between the boglands of Connemara to the west and the limestone country approaching Galway to the east. The tower's six storeys rise from the remains of the double bawn, its bartizans jutting from the corners like stone sentinels. The banqueting hall, though ruined, retains carved reliefs of grapevines -- a decorative motif that speaks to the O'Flahertys' trade connections with continental Europe and their aspirations beyond the rough reputation that Galway's city fathers attributed to them. Today the castle is managed by the Office of Public Works and open to visitors from March through November. It is a quieter attraction than some of Ireland's more famous castles, which is part of its appeal: the tower house stands in relative solitude, as it has for five centuries, watched over by the Connemara hills and the wide grey waters of Lough Corrib.