Built around 1660 by the O’Brien family, this fortified house represents a fascinating transitional period in Irish architecture, when the need for defence was beginning to give way to more comfortable domestic arrangements. The castle’s distinctive design features both defensive elements like narrow windows and thick walls, alongside more refined residential touches that hint at changing times.

The O’Briens, who constructed Glen Castle, were one of the most powerful Gaelic families in Clare, descendants of Brian Boru, the legendary High King of Ireland. Their decision to build this particular structure in the mid-1600s came during the aftermath of the Cromwellian conquest, when many Irish landowners were struggling to maintain their estates. The castle served as both a family home and a symbol of resilience, allowing the O’Briens to maintain their presence in the region despite the political upheavals of the period.

Today, Glen Castle remains remarkably well preserved for a structure of its age, with its main tower house still largely intact. The building showcases typical features of Irish tower houses from this era, including vaulted ceilings on the ground floor and a spiral staircase connecting the various levels. Local historians note that the castle’s position in Glen South provided strategic views across the surrounding countryside, whilst its proximity to water sources and fertile land made it an ideal location for a family seat. Visitors to the site can still trace the outline of what would have been the bawn wall, which once enclosed the castle’s courtyard and auxiliary buildings.