Built by the Mac Carthys of Gleann an Chroim, probably in the late 16th century, this rectangular tower measures 16.2 metres east to west and 9.7 metres north to south. The structure features an unusual architectural element; its spiral staircase winds around a central circular masonry column, 0.88 metres in diameter, that rises through the full height of the building. At the foot of these stairs lies a tiny, unlit chamber measuring just 2 by 1.4 metres, known locally as ‘chambrin á chodaigh’, or ‘the tyrant’s little room’.

The tower’s internal layout reveals careful planning across its four floors. The ground level, accessed through a doorway near the southern end of the eastern wall, opens into a lobby that leads to the main chamber. Each of the upper three floors contains a principal chamber lit by pairs of windows in the north and south walls, with fireplaces built into the eastern walls. The third-floor windows are particularly notable for their square-headed design with central mullions. The first and second floors feature additional smaller chambers accessed through secondary doorways, built over the ground-floor lobby area. A pointed vault with wicker centring spans north to south over the first-floor chamber above the lobby, whilst the room above this vault, complete with its own fireplace, is known as ‘chambrin-na-banaltran’, or ‘the little chamber of the nurse’.

Though time has obscured some details, the tower once boasted bartizans over its northwest and southeast corners, supported by tapering masonry corbels. In the late 19th century, the castle underwent significant alterations when it was converted for use by a small local industry; a corrugated iron roof was installed, and chimney stacks were added, including a large one atop an internal partition wall and smaller ones on the eastern and western gables. These chimney stacks feature distinctive zig-zag plans similar to those found on 17th-century fortified houses at Coolnalong and Reenadisert, suggesting later modifications that followed contemporary defensive architectural trends.