Built by the MacNamara clan, who controlled much of eastern Clare for centuries, the castle served as both a fortified residence and a symbol of their considerable power. The structure rises five storeys high, with thick limestone walls that have weathered nearly 500 years of Irish winters.

The castle’s design follows the typical pattern of Irish tower houses, featuring a single main chamber on each floor connected by a narrow spiral staircase built into the wall’s thickness. Murder holes above the entrance, narrow arrow slits for defence, and a machicolation at roof level all speak to the violent realities of clan warfare in medieval Ireland. The ground floor, originally used for storage, has a stone vault ceiling; a common feature that prevented fire from spreading upward and provided structural support for the floors above.

What makes Clenagh particularly noteworthy is its relatively complete state of preservation, including intact bartizans (corner turrets) and much of its original oak timber work. The MacNamaras abandoned the castle in the 1650s during the Cromwellian conquest, after which it passed through various hands before falling into disuse. Today, it stands on private farmland, its grey stone walls rising from the surrounding fields as a remarkable survivor of Ireland’s turbulent past. Visitors should note that access requires permission from the landowner, though the castle can be viewed from the nearby public road.