What survives today is the western side of a polygonal keep, rising two storeys high alongside sections of curtain wall, all constructed from neatly coursed limestone blocks with distinctive slate packing. The castle stands at the eastern end of an earthen motte, its walls now heavily cloaked in ivy and bearing the scars of time; substantial stones have gone missing from its base, likely damaged during past attempts at ivy removal.

This fortress was built around 1174 by Sir Hugh Tyrell, who served as Governor of Trim, marking the Norman push to control the strategic lands around Dublin. The castle witnessed one of its most dramatic moments in 1316 when Edward Bruce, brother of the Scottish king Robert, laid siege to it during his campaign to become High King of Ireland. A sketch from 1698 reveals how much grander the structure once was, depicting a four-storey tower complete with battlements, defensive base batter, and large first-floor windows; a far cry from today’s ruins.

The architectural details that remain offer fascinating glimpses into medieval defensive design. Above the western opening, traces of machicolation can still be spotted; these projecting galleries once allowed defenders to drop stones or boiling liquids on attackers below. A straight seam where the keep meets the curtain wall suggests the castle was built in two distinct phases. The curtain wall itself, standing 2.6 metres high, encloses an irregular area roughly 30 metres east to west and 20 metres north to south, which now serves as a cemetery for the Vincentian Order. Look closely and you’ll find remnants of a vaulted opening at the junction of keep and wall, the remains of a garderobe chute, and an undercut inner wall face; all practical features of a working medieval fortress.