This medieval stronghold, dating from the 13th century, was built by the Anglo-Norman Jordan de Exeter following his conquest of the area. The castle takes its name from the O’Connor clan, who held power in the region before the Norman invasion and would later reclaim the fortress during various periods of Gaelic resurgence.

The castle’s strategic position overlooking the River Moy made it a coveted prize during Ireland’s turbulent medieval period. Throughout the 14th and 15th centuries, control of Castleconnor shifted repeatedly between Anglo-Norman lords and Gaelic chieftains, with the O’Dowds and MacDermotts joining the O’Connors in the struggle for dominance. The fortress witnessed its share of sieges and battles, including a notable attack in 1470 when the O’Connors successfully recaptured it from the de Burgos, only to lose it again within a generation.

Today, visitors can explore the substantial remains of the tower house and bawn wall, which offer glimpses into the castle’s defensive architecture. The ruins sit amongst farmland, largely forgotten except by local historians and the occasional walker who stumbles upon this remnant of Mayo’s feudal past. Though roofless and weathered, the thick limestone walls continue to stand firm; a reminder of the power struggles that once shaped this corner of Connacht.