This limestone fortress, measuring 15 metres by 12.6 metres with walls nearly a metre thick, showcases the defensive architecture typical of medieval Ireland. Though much of the northern portion has collapsed, including the original doorway, the remaining structure reveals sophisticated construction techniques. The ground floor features a north-south barrel vault with evidence of a former loft space, whilst the upper levels contain various mural passages and chambers within the thick walls. Particularly notable are the chambers in the southeast and southwest angles, where remnants of wicker-centring used during construction can still be observed, along with a substantial cut-limestone fireplace on the second floor of the eastern wall.

The castle’s defensive capabilities extended well beyond the tower house itself. A remarkable seven-sided bawn wall, stretching approximately 80 metres north to south and 60 metres east to west, encircles the complex with gun loops positioned at strategic points. Between this outer wall and the tower house stood an inner defensive wall complete with angle towers, though much of this secondary fortification has been destroyed on the northern and eastern sides. Historical records by Carrigan mention intriguing features that have since vanished, including a sheela-na-gig carved into the eastern wall and a draw-well in the courtyard centre, though neither can be seen today.

Like many Irish castles, Galesquarter suffered significant damage during the Cromwellian conquest in the mid-seventeenth century, rendering it uninhabitable. The tower’s upper levels were supported on wall thickness, with the surviving southern wall showing evidence of a wall-walk and pitched gable, whilst a chimney stack adorns the eastern wall. Most window openings throughout the structure are simple rectangular apertures, typical of the period’s functional military architecture. Despite centuries of abandonment and decay, the castle remains an impressive testament to the power and architectural skill of the MacGillapatricks, who once controlled this strategic stronghold in medieval Laois.