Today, this surviving masonry forms part of a garden wall overlooking Cappercullen Glen, its southeastern face displaying a distinct batter, or sloping profile, built to support the structure against the steep slope. The wall features alternating quoin stones at its angles, with the lower footings of a southwestern return wall still visible. Where the original castle once stood, approximately 40 metres to the west, modern tennis courts now occupy the site of the later Cappercullen House, which was itself demolished in recent times.

The history of Cappercullen Castle stretches back to at least the 16th century, when Henry Mac Lysagh O’Mulrian held the lands and received a royal pardon in 1569. By 1604, the castle and its estates had passed to Theobald Baron Bourgh of Castleconnell, formerly belonging to the O’Mulrian family. The 1656 Down Survey map depicts ‘Capacullyn’ as a tower house with a battlemented parapet, standing alongside two thatched houses and several cabins. During the turbulent 1640s and 1650s, Colonel Pierce Walsh of Abbeyowney controlled the 261 acres of profitable land and 33 acres of bog that comprised the estate. Following the Cromwellian confiscations, the forfeited property was granted to George Evans in 1667.

The site underwent significant transformation in the centuries that followed. Around 1680, a walled garden was constructed west of the medieval castle, and Lord Carbery built Cappercullen House in the early 18th century. Some intriguing architectural details suggest the recycling of medieval materials; quoin stones in the garden sheds of the walled garden display chamfered surfaces that may have originated from the medieval castle itself. The wall visible today corresponds to a building shown on the 1840 Ordnance Survey map, depicted as a narrow rectangular structure running parallel to the river valley, serving as one of several outbuildings associated with the later house. While the grand house and medieval castle have vanished, these fragmentary walls and repurposed stones offer tangible connections to Cappercullen’s layered past.