The site consists of a walled courtyard measuring approximately 30 by 40 metres, with a square tower house positioned at the northwest corner. Though time and weather have taken their toll; Hurricane Ophelia caused partial collapse of the walls in October 2017; enough remains to trace the outline of this substantial fortification. The tower’s north wall still rises about 9 metres high, its 1.4 metre thick walls testament to the solid construction methods of its builders. Stone steps at the northeast corner of the bawn once provided access to the wall tops, allowing defenders to patrol the perimeter.

Historical records paint a picture of the castle’s changing fortunes through the centuries. Originally a possession of the earls of Kildare, the property passed through marriage to Sir Drury Wray before being held by Sir William Parsons in 1624. By 1641, according to the Civil Survey, the lands belonged to Mrs Ann Casey, a Protestant landowner, and the estate then included not just the castle and bawn but also an orchard. When the Ordnance Survey documented the site in 1840, they found the western dwelling house still inhabited, albeit thatched and occupied by a poor family, whilst the main tower stood largely ruined with only fragments of its walls remaining.

Aerial photography and satellite imagery have revealed intriguing features beyond the visible stone ruins. The footings of a large rectangular area to the west, measuring roughly 75 by 28 metres, may represent the walled garden or orchard mentioned in the 17th century survey. Evidence of a possible hollow way or ancient road can be detected to the east, along with traces of what might be former house sites northeast of the castle. These ghostly outlines in the landscape, visible only from above, hint at a once thriving settlement clustered around this defensive stronghold, adding another layer to Rathcannon’s long and varied history.