Constructed around 1582 by Cork’s citizens to protect the city from pirates and invaders, the tower originally measured 10.5 metres in diameter and was built directly onto the rock. Today, visitors encounter a fascinating blend of historical periods; the original 16th-century structure now forms the northern anchor of a neo-Gothic complex added in 1828-29 by architects James and G.R. Pain. The ground floor, with its interior diameter of 6 metres, features five evenly spaced embrasures that were purpose-built gun ports, their double-splayed openings covered by segmental arches on the inside and inclined lintels on the outside. These defensive features, now blocked up, once allowed cannons to command strategic positions along the river approach to Cork.

The castle’s evolution tells a compelling story of Cork’s changing fortunes and architectural tastes. Eighteenth-century paintings reveal that the tower once stood at least two storeys higher than its original defensive structure, topped with what contemporary accounts described as a ‘handsome octagon room’ and an adjoining gable-ended house. The current complex, entered through an embattled gateway bearing a stone plaque commemorating the 1828-29 rebuilding, showcases the Victorian enthusiasm for Gothic revival architecture. The original circular tower now supports a slimmer tower rising three additional storeys, complete with a turret containing spiral stairs, whilst an elaborate water-gate on the eastern side leads to a slipway. Throughout the 18th and 19th centuries, Cork Corporation used the castle for civic entertainment and functions, transforming what began as a military fortification into a social venue.

An unexpected historical treasure awaits in the first-floor foyer, now part of a bar and restaurant; a carved stone fireplace rescued from the demolished Ronayn’s Court. This remarkable piece features a large lintel with a shallow elliptical arch and edge roll moulding, bearing an inscription that reads “Morris Ronayn and Margaret Gould builded this house in the yeare of oure lorde 1627 and in the 3 yeare of Kinge Charles. Love god and neighbors.” The lintel displays the IHS monogram flanked by family armorial shields, fleurs-de-lis, and a Tudor rose, offering visitors a tangible connection to Cork’s merchant families and their role in shaping the city’s built heritage during the early 17th century.