The Georgian house, constructed in 1736, was deliberately built atop the ruins of a 17th-century castle, effectively concealing the earlier structure from view. Whilst the castle itself is no longer visible at ground level, one remarkable piece of evidence survives: a carved datestone, now incorporated into the back wall of the house, that once formed the top of a window frame in the original fortification.

The inscription on this weathered stone tells a precise story: “DERMOT COGHLAN MADE THIS CASTELL IN ANNO DNI 1627”. This single line of text reveals both the castle’s builder and its exact construction date, providing a tangible link to the Coghlan family who once controlled this part of Offaly. The original structure was likely a fortified house or tower house, a common defensive dwelling type in 17th-century Ireland, built during a period when such fortifications were still necessary for local landowners seeking protection during uncertain times.

Today, Ballycumber House stands as an elegant example of 18th-century architecture, giving little indication of its martial predecessor buried beneath. The repurposed datestone serves as the sole visible reminder of Dermot Coghlan’s castle, a poignant example of how Ireland’s built heritage often exists in layers, with each generation building quite literally upon the foundations of the last. This practice of incorporating elements from earlier structures into newer buildings was both practical and symbolic, allowing families to maintain connections to their ancestral past whilst adapting to changing architectural fashions and political climates.