Built from roughly coursed limestone, this rectangular fortress measures approximately 16.9 metres north to south and 10.35 metres east to west, with walls over two metres thick. The O’Phelans maintained ownership of the castle from its construction until the mid-seventeenth century, establishing it as a significant stronghold in the region alongside the nearby church, which lies just 250 metres to the northeast.

The castle’s defensive architecture reveals the careful planning that went into its construction. The original entrance, now broken out, was positioned at the eastern end of the south wall and featured a murder hole overhead; a grim reminder of the violent times in which it was built. The interior showcases remarkable engineering with a great barrel vault stretching the entire length of the building above the first floor, reaching 22 feet at its apex according to historical records from 1905. The structure incorporates an intricate system of mural passages and stairs built into the thickness of the walls, with the main stairway contained within the south wall leading from the entrance to the upper floors. Unlike many Irish tower houses of the period, none of these staircases are spiral, instead running straight through the massive walls.

The castle’s walls contain numerous chambers and passages that speak to both its defensive capabilities and daily function as a residence. Three vaulted areas feature openings in both the eastern and western walls, whilst the first floor’s eastern wall displays four rectangular openings aligned horizontally. The varying thickness of the walls, ranging from 7 feet to over 9 feet in places, not only provided structural support for the impressive stone vault but also allowed for the incorporation of multiple stairways and long passages within the walls themselves, creating a complex internal layout that would have served both practical and defensive purposes.