Before the waters claimed it, archaeologist Fahy conducted a thorough survey and excavation in 1957, documenting a castle that had already fallen into considerable ruin, with only its south-east angle remaining at full height. The tower measured 18.7 metres tall and featured two projecting rectangular towers; one at the north end of the east wall and another at the south end of the west wall, creating an asymmetrical but formidable defensive structure.

The castle’s interior revealed a complex arrangement of chambers and passages typical of late medieval Irish tower houses. Visitors would have entered through a ground-floor doorway near the west end of the north wall, stepping into a chamber lit by windows with double-splayed embrasures. The ground floor contained multiple recesses with rounded, wicker-centred heads, whilst a door in the west wall led to a vaulted chamber within the south-west tower. A particularly clever feature was discovered in the north-east corner; a mural passage that widened into a corbelled chamber with a narrow slit that served as both ventilation and a service hatch to the main chamber. The upper floors were accessed via mural stairs, with the first floor featuring a rounded vault, a fireplace with wall-oven, and what appears to have been garderobe facilities. The defensive capabilities extended to the surrounding bawn wall, which enclosed a trapezoidal area around the tower, complete with a small defensive tower near the south-east corner equipped with slit openings for flanking fire.

Built by the Barretts in the latter half of the 15th century, Castle Inch witnessed the turbulent politics of Munster when the Mac Carthys forcibly seized it in 1593, maintaining control until the late 17th century. During excavation, Fahy’s team uncovered telling artefacts amongst the debris, including dressed limestone corbels from a machicolation, window sills, voussoirs from a collapsed arch, and notably, a clay tobacco-pipe bowl dating to the second half of the 17th century, offering a tangible link to the castle’s final occupied period. By 1750, the castle had already fallen into ruin, beginning its long decline that would end two centuries later beneath the waters of a hydroelectric reservoir.