Known today as Castle Wellington, the structure was originally called Killowney until the early eighteenth century, when a landlord named Wellington built an adjacent house and bestowed his name upon the ancient fortification. The Civil Survey of 1654-6 recorded it as a ‘castle with a Barbicon’, with Rory O’Kennedy listed as its proprietor in 1640, placing it firmly within the tumultuous period of Irish history when such defensive structures were essential for survival.

The limestone tower, measuring approximately 12 metres north to south and 9.25 metres east to west, originally rose four storeys high with a clever defensive design that would make any attacker think twice. The main entrance on the western wall features a pointed doorway with a yett-hole; essentially an iron gate that could be dropped to seal the entrance; leading to a lobby overlooked by a murder-hole where defenders could rain down unpleasantries on unwelcome visitors. Beyond this deadly welcome mat, a spiral staircase in the northwest corner provided access to the upper floors, whilst the ground floor housed a main chamber and guardroom. The second floor boasts an east-west barrel vault, a remarkable feat of medieval engineering, whilst the floors above and below were originally supported by timber beams resting on corbels.

What makes this tower house particularly fascinating is how it evolved over time, with an extra floor cleverly inserted early in the seventeenth century to maximise living space. The building reveals layers of domestic life through its architectural features: garderobes tucked into the walls, slop-stones for waste disposal, window seats that doubled as defensive positions, and even pigeon boxes added in later centuries for a ready source of fresh meat and eggs. The defensive elements remain impressive; bartizans project from the northeast and southwest corners, whilst a machicolation over the west wall allowed defenders to drop objects on attackers below. At parapet level, accessed via mural stairs that become spiral in the northwest corner, a caphouse provided shelter for sentries keeping watch over the surrounding countryside, with a covered gallery that once ran along the western wall, though little of it survives today.