The castle, whose Irish name An Coinicéar translates to “rabbit warren”, appears on the 1840 Ordnance Survey map as merely a notation reading “Site of Nicker Castle”, suggesting that even by then, no visible traces remained above ground. Local tradition held that the fortress once belonged to the McBrien family of Coonagh, though this claim lacks supporting documentary evidence.

The historical record for Nicker Castle proves frustratingly thin. When antiquarian Thomas Johnson Westropp surveyed the area in the early 1900s, he expressed considerable doubt about the site’s authenticity, noting that whilst foundations were claimed to mark a castle in 1840, he could find no corroboration in maps, surveys, or records that were otherwise quite detailed about other fortifications in the region. The 1840 field notes describe the location as being on rocky, rising ground near the small village of Nicker, but emphasise that “not a vestige of it now remains”.

Today, visitors to the site will find a large quarry with a sheer, ivy-covered cliff face on its western side, with the quarry entrance facing east. The 1897 Ordnance Survey map shows extensive quarrying operations immediately north and east of where the castle supposedly stood, and it seems likely that any remnants of the medieval structure were destroyed by post-1700 stone extraction. Whether Nicker Castle was a substantial fortress or merely a minor tower house remains unknown; its very existence rests solely on local memory and a handful of map annotations.