Today, only the western and southern walls survive from this once-imposing structure, though careful observation reveals foundation traces of the two missing walls. The castle represents a typical example of 16th-century Irish defensive architecture, built during a period when such fortified residences were essential for protecting landed wealth and political power.

The remaining walls offer fascinating glimpses into medieval construction techniques. A substantial barrel vault stretches from the south wall over what was the first floor, whilst embrasures and aumbries; small wall recesses used for storage; can still be spotted at both ground and first-floor levels. Perhaps most intriguingly, traces of wicker centering remain visible in the barrel vault and embrasure soffits, providing rare evidence of the temporary frameworks used by medieval builders to support stone arches during construction. The original entrance and stairwell, which would have been located on either the eastern or northern side, have unfortunately vanished entirely.

Since 1940, Fassaroe Castle has been protected under a preservation order through the National Monuments Acts, recognising its significance to Ireland’s architectural heritage. Archaeological surveys conducted for the County Wicklow inventory have helped piece together the castle’s story, though much about daily life within its walls remains a mystery. The ruins serve as a tangible link to the Tudor period in Ireland, when figures like Brabazon navigated the complex political landscape between English administration and Irish lordships.