What it quietly erases from view, however, is something considerably older. Beneath its foundations, or rather displaced by them entirely, once stood a 17th-century house belonging to one of the most powerful figures in early modern Ireland.

According to the architectural historian Maurice Craig, writing in 1969, the site on which City Hall now stands was previously occupied by a house built by the Earl of Cork. That title belonged most famously to Richard Boyle, the first earl, who arrived in Ireland in 1588 with very little and systematically accumulated land, property, and influence on a scale that made him one of the wealthiest men in the British Isles by the early 17th century. Boyle was a relentless builder and acquirer of urban and rural property across the country, and a house in this part of Dublin, close to the administrative and commercial centre of the city, would have been entirely consistent with his documented habits. The house itself is gone without trace, swallowed first by the changes of the intervening decades and then definitively by the construction of the Royal Exchange, as City Hall was originally known, which was completed for Dublin's merchant community in the late 18th century.

City Hall itself sits at the top of Dame Street, just at the Castle Gates, and is open to the public most days. The ground floor houses a permanent exhibition on Dublin's history, and the great circular entrance hall, with its columns and mosaic floor, is worth the visit on its own terms. There is nothing visible of the earlier structure; no exposed stonework, no interpretive marker pointing to what preceded the Exchange. The interest here is largely one of layered imagination, standing in a well-known civic space and knowing that something altogether different once occupied the same ground, associated with a man whose influence over 17th-century Ireland was enormous and whose presence in the built fabric of the city has otherwise largely disappeared.