At its heart stands the poorly preserved remains of a rectangular tower that once served as Castle Mahon, the chief residence of the Kinalmeaky branch of the O’Mahony clan. The tower, which you can still identify by its ground floor entrance with a pointed arch doorway in the north wall (now blocked), features a wicker-centred vault running north to south over the ground floor. The O’Mahonys themselves burnt the castle in the 1580s rather than see it fall into Crown hands after confiscation, a defiant act typical of the period’s fierce resistance to English rule.

Around 1798, the old tower was incorporated into a new structure; Castle Bernard House, an ambitious Georgian mansion. The house boasted two storeys and a nine-bay front with a distinctive deep central bow to the rear. Around 1815, the owners added fashionable Gothic Revival touches including battlements and turrets, connecting the ancient tower to the west side of the house via a corridor. This blend of medieval fortress and Georgian elegance represented the changing face of Irish landed estates, where new money often built upon old foundations.

Today, both structures stand roofless and haunting, the house having been burnt around 1921 during the turbulent years of the Irish War of Independence and Civil War. Despite heavy modifications over the centuries, you can still trace the evolution of this site from medieval stronghold to Georgian mansion to protected monument. The ruins are now subject to a preservation order, ensuring that this remarkable palimpsest of Irish history, with its tales of clan loyalty, architectural ambition, and political upheaval, remains for future generations to explore and interpret.