The castle's construction likely began around 1546, evidenced by a bridal mantlepiece tree commemorating James Barnewall's marriage to Margaret Lawrence that year. Though the Confederate Wars of 1641 left it severely damaged, earning it the designation of a 'burnt castle' in the Civil Survey of 1654-6, the structure was subsequently renovated and continues to evolve today under the careful stewardship of Fingal County Council's Parks Department.

The castle comprises an L-shaped range of buildings, with the main east-west block measuring 22 metres in length and featuring coursed masonry construction with dressed limestone quoins. The ground floor retains its original barrel vault, complete with traces of wicker-centring, whilst various defensive and domestic features tell the story of its dual purpose as both home and fortress. Gun loops pierce the walls, slit openings and round-headed limestone windows provide light, and practical elements like a bread kiln in the southern chamber reveal daily life within these walls. An 18th-century drawing by Austin Cooper shows the castle once rose to four storeys, with a watch tower at the northern end containing small vaulted chambers and a spiral staircase that extended even higher, alongside a projecting garderobe tower on the eastern elevation.

Archaeological investigations have revealed further layers of history beneath and around the castle. Monitoring work in 1995 uncovered stone-built channels linked to the garderobe and drainage systems, whilst a 2011-12 resistivity survey identified numerous anomalies within the walled garden, including what may be remnants of a medieval walled enclosure, internal pathways, and possibly a well or water feature. Today's reimagined structure stands five storeys tall, with only part of the ground floor remaining from the original construction; modern conservation efforts have added decorative features, embellishments and turrets that both preserve and reinterpret this significant piece of Irish heritage for future generations.