Known locally as Clonmel Castle, this medieval structure was part of the Court of the Palatinate, a significant administrative centre in medieval Ireland. The castle survived centuries of Irish history before meeting its end around 1810, when local man John Harvey decided to demolish it entirely.

By 1936, when historian Lyons conducted his survey of the area, only fragments remained of what had once been a substantial fortification. At that time, the site housed Tangney's drapery shop, and Lyons claimed to have identified what he believed was the eastern wall of the old castle, sandwiched between Tangney's and the neighbouring Woolworth Building. His observations provide one of the last documented sightings of any physical remnant of the castle above ground.

Today, visitors to O'Connell Street will find no visible trace of this once prominent structure; the castle has been entirely absorbed by the town's commercial development. The site serves as a reminder of how completely Ireland's medieval heritage can disappear beneath the ordinary streetscapes of modern towns, leaving only archival records and the occasional archaeological survey to hint at what once stood there.