This imposing structure rises five storeys high, its walls featuring carefully dressed quoins; the worked corner stones that demonstrate the skill of medieval stonemasons. The tower exhibits a slight base batter, where the walls gently slope outward at ground level, a defensive architectural feature that helped strengthen the structure against both siege weapons and the passage of time.

The castle’s defensive capabilities extended beyond its sturdy walls. To the southwest of the tower house, earthworks remain visible in the landscape, likely marking the boundaries of what historians believe was a bawn; an enclosed courtyard that would have provided protection for livestock and storage buildings during times of conflict. These earthen remnants offer tantalising glimpses into how the castle complex would have functioned as both a residence and a defensive stronghold for the Fitzpatrick family, who were prominent landowners in the region during the medieval period.

First documented by Carrigan in 1905, Ballagh Castle represents the power and influence of Gaelic Irish families who adapted Norman building techniques to create their own distinctive architectural legacy. These tower houses, built primarily between the 15th and 17th centuries, served as symbols of authority whilst providing practical defence in an era of frequent territorial disputes. Today, the castle stands as a testament to this turbulent period of Irish history, its weathered stones bearing witness to centuries of change in the Laois countryside.