Built by the O’Callaghans on the site of an earlier castle, this extensive fortification consists of three main structures connected by walls and gateways, all contained within a large trapezoidal bawn covering approximately 1.85 hectares. The main house, a three-storey building with an attic, features distinctive Renaissance architectural elements including symmetrical windows with mullions along its river-facing northern wall and defensive box machicolations positioned strategically around the upper levels. The house was originally accessed through doors on the south wall, likely via a now-lost stair tower, and contained two main chambers on each floor separated by internal stone walls.

The complex reflects the political landscape of early 17th-century Munster, when Irish families like the O’Callaghans and their overlords, the MacDonagh MacCarthys, aligned themselves with English interests following the suppression of late 16th-century rebellions. Both families invested in constructing fortified houses around the same time, with nearly identical Renaissance-style doorways at Dromaneen and the MacCarthys’ castle at Kanturk, possibly carved by the same mason. The ornate gateway connecting the buildings features a semi-elliptical arch topped by an entablature with frieze and cornice, similar in style to dated examples from 1636 at Kanturk and Monkstown Castle. The defensive nature of the complex is evident throughout; gun loops pierce the walls of the corner towers and semi-circular projections, whilst the massive bawn walls, reaching up to four metres in height, originally featured corner towers including one documented as containing a columbarium with thirteen tiers of nesting boxes.

Today, the castle stands as a National Monument under state guardianship, having undergone extensive repairs by the Office of Public Works in the 1940s. Despite the loss of some features, including the southeast corner tower demolished in 1906 for its stone and part of the eastern bawn wall that collapsed in 1997/98, the complex remains one of Cork’s most significant examples of early modern fortified domestic architecture. The surviving structures include the main house with its attached western extension and flanking tower, a separate rectangular building to the east, and substantial portions of the defensive bawn walls with their remaining towers and projections, all testament to the wealth and strategic importance of the O’Callaghans in this region during a period of significant political and social transformation.