The structure likely dates from around 1617, when Richard Cosby leased the lands of Ballymaddock to John Allen for twenty years. The original castle appears to have been built during this period, though by the time John Weaver occupied it in 1691, it had already begun its transformation from fortified residence to country house. Weaver, an active supporter of William III during the Williamite Wars, lent his name to the building, which local people still called “Squire Weaver’s House” well into the 19th century. The house also sheltered Charles O’Dempsey, nicknamed Cahir-na-capul, during a period of political upheaval, giving the ruins their alternative name.

The original structure was a T-shaped house with considerable defensive features, including a courtyard or bawn with square corner towers and walls of remarkable thickness. Archaeological evidence suggests it consisted of just two storeys, with distinctive open chimneys running up the gable walls that terminated in angular square flues; a characteristic architectural detail of the period. The severe winter storm of 1852 caused significant damage to the already deteriorating building, with portions of the gable collapsing internally. Subsequently, much of the old castle was pulled down, its stones repurposed to construct a dwelling house within the former courtyard.

Today, the northern half of the building has been modernised and remains inhabited, whilst the southern portion stands in ruins, its tall ivy-clad chimney stack and rubble-built fireplace still visible in the southeast corner. Remnants of the bawn walls can be traced running east to west from the house’s southeast corner, and two gabled outbuildings with pronounced base batters survive at the northwest, complete with what appears to be a gun loop; a reminder of the property’s defensive past. These atmospheric ruins, marked on Ordnance Survey maps simply as “the house of Cahir-na-capul, in ruins”, offer a tangible connection to centuries of Irish rural life, from plantation-era fortified houses through Jacobite conflicts to the agricultural landscapes of the 19th century.