An 1853 sketch based on an original 1650 plan reveals what was once a formidable Fitzgerald stronghold under siege during the Confederate War (1641-53). The castle itself was an impressive structure: a large double-gabled building of three storeys plus attic space, complete with crenellations along its northern facade. A rectangular crenellated tower projected from the centre of the north wall, whilst a tall circular turret jutted from the southwest corner, strategically positioned to overlook one of the two entrances.

The castle occupied the northeast corner of a well-fortified square bawn, enclosed by crenellated walls with defensive towers at the northwest and southeast corners. Access to this stronghold was carefully controlled through two entrances; the main one beneath the southwest turret, and a second midway along the northern wall, complete with a drawbridge or causeway. This inner defensive complex didn't stand alone; it was further protected by a bastioned fort that encompassed not just the castle and bawn, but also a nearby motte and church to the north.

What makes this site particularly intriguing is how comprehensively it was documented in that 1650 plan, capturing the castle at a pivotal moment when it came under attack during one of Ireland's most turbulent periods. Though the physical structures have long since vanished from the landscape of Ballyshannon Demesne, the detailed historical record compiled by Gearóid Conroy provides a window into the sophisticated defensive architecture employed by the Anglo-Norman Fitzgeralds in medieval Kildare.