This round tower house, dating from the late sixteenth century, rises three storeys high, though much of the upper levels have fallen into ruin. Built from roughly coursed limestone blocks, the structure measures six metres across internally, with walls an impressive three metres thick; a defensive necessity in turbulent times.

The castle’s eastern entrance reveals the defensive mindset of its builders. Visitors pass through a pointed doorway, complete with a yett-hole in the southern jamb for securing an iron gate, before entering a lobby overlooked by a murder-hole. From here, a second lobby provides access to both the spiral stairs in the south wall and the main ground-floor chamber to the west. This principal room, reached through a round-headed doorway, receives light from three flat-headed windows set within large rectangular embrasures. The first floor, which once rested on wooden beams, features a corbelled dome ceiling and four round-headed windows. A doorway in one of the eastern window embrasures leads to a small mural chamber containing the murder-hole mechanism, allowing defenders to attack intruders trapped in the entrance lobby below.

Though ivy now obscures much of the exterior, careful examination reveals sophisticated architectural details that speak to the skill of its late Tudor-era craftsmen. The stonework displays punch tooling and drafting, whilst practical features like hanging-eyes and the remains of a garderobe chute in the southwest wall demonstrate both defensive and domestic considerations. The spiral stairs, lit by small flat-headed loops, have unfortunately collapsed above the first floor, but what remains of Rathurles Castle provides a tangible connection to the fortified dwellings that once dotted the Irish countryside during a period of considerable upheaval.