Built from split stone and marine mortar, the rectangular castle measures roughly 10 by 8 metres and rises from a distinctive battered base. Though historical records remain frustratingly sparse, the castle is believed to have belonged to the MacCarthy clan before possibly passing to the Sigerson family in the early 1600s. Its story appears intimately connected with the nearby Ballinskelligs Priory, with various documents from the late 16th and 17th centuries referencing the leasing and garrisoning of both structures.

The castle's defensive features reveal the paranoia of its age: a pointed sandstone doorway could be secured by both a hinged grille and heavy door, whilst visitors entering the lobby would find themselves beneath a murder hole, perfect for dispatching unwelcome guests. The ground floor chamber, known locally as Seomra an Bhoduig, was accessed through a distinctive 'Caernavon type' doorway; a sophisticated entrance where the lintel rests on projecting corbels. A clever mural staircase in the building's southern angle winds upward, providing access to the upper floors. Each level contained a main chamber with adjoining passageways, lit by narrow loops and windows that were later enlarged, possibly for comfort over defence.

Archaeological excavations in 1988 and 1991 uncovered the original paved ground floor beneath layers of storm deposits, along with evidence of later lean-to structures with cobbled floors. The external walls once supported additional buildings; beam sockets along the northwest wall suggest these may have been press beams for a 17th-century pilchard curing station, possibly connected to Sir William Petty's documented fishery operations at Ballinskelligs. Though the castle's roof and upper sections have long since vanished, what remains offers a fascinating glimpse into the practical realities of late medieval Irish life, where comfort, defence, and commerce all competed for space within these thick stone walls.