The only evidence of its existence comes from historical maps, most notably Duncan’s 1821 survey, which marks the site as “Rowlagh Castle, defaced”; a cartographer’s way of noting that the structure was already in ruins by the early 19th century.

The castle’s complete disappearance represents a common fate for many of Ireland’s lesser fortifications, particularly those that fell into disrepair before the Victorian era’s antiquarian movement could document them properly. Unlike more prominent castles that were maintained or at least left as picturesque ruins, Rowlagh was likely quarried for building materials as the surrounding area developed, its stones recycled into local houses and walls until nothing remained above ground.

Today, residents of the housing estate built on the castle’s footprint might be completely unaware they’re living atop centuries of history. Without archaeological excavation, we can only speculate about what lies beneath the tarmac and foundations; perhaps medieval foundations, defensive ditches, or other remnants of the castle complex that once controlled this part of Dublin’s hinterland. It serves as a reminder that Ireland’s historical landscape often lies hidden beneath the modern world, recorded only in old maps and place names.