Known as Desmond Castle after the Fitzgerald family arms carved above its doorway, this urban tower house is one of only 40 such structures surviving in Ireland. Built as a town residence by the Fitzgeralds, the castle has witnessed centuries of dramatic history, from its role as a magazine storing weapons and gunpowder during the Spanish occupation before the Battle of Kinsale in 1601, to its grim transformation into a prison for foreign captives. The building earned its alternative name, the ‘French Prison’, after housing numerous foreign prisoners over the years, many of whom tragically perished in a fire that swept through the building in 1747.

The castle served as the borough jail from 1791 to 1846 before falling into disuse. After being declared a National Monument in 1938, it underwent extensive restoration by the Office of Public Works. Early 20th-century photographs reveal significant changes to the structure; the street-facing gable that once topped the second floor has been replaced with battlements, rendering has been stripped away, missing mullions have been restored, and ground floor windows have been blocked up. The building’s architectural details tell their own story, with the central ground floor door featuring a pointed arch and hood moulding with floriated stops, possibly added after the original construction. The first floor showcases two central windows with ogee heads, divided by mullion and transom, whilst similar windows with rounded arches sit at the corner angles.

Today, this National Monument stands as a testament to Kinsale’s turbulent past, its stone walls having served variously as aristocratic residence, military storehouse, prison, and now museum. The castle’s evolution from private dwelling to public monument reflects the broader sweep of Irish history, from medieval clan power through colonial conflict to modern heritage preservation. Its sturdy walls and carefully restored features continue to draw visitors interested in the layers of history embedded in this remarkable urban tower house.