Before it became a parliament house, and long before it became a bank, this prominent site was occupied by a hospital for injured soldiers, a function that has left almost no trace on the streetscape or the popular imagination.

The original structure was known as Careios Hospital, built after 1602 to house soldiers maimed in the wars of the late Elizabethan period. It appears on John Speed's map of Dublin dated 1610, by which point it was already described as a substantial three-bay building. Within a few years it had acquired a gatehouse, a courtyard, and an enclosing wall, giving it something closer to the character of an institutional compound than a simple infirmary. The building's career took an unexpected turn in 1661, when it became the location for the first parliament held in Ireland under the restored monarchy, a detail that makes its earlier medical purpose all the more incongruous. The present structure on the site dates from 1729, built when the earlier hospital building was replaced entirely.

The site sits on College Green, directly opposite Trinity College Dublin, and is straightforward to find. The 1729 building, which served as the Irish Parliament House before the Act of Union transferred legislative power to Westminster, is now open to the public as a working bank, and parts of the interior, including the former House of Lords chamber, can be visited during banking hours. Nothing visible at street level signals the hospital that preceded it, so the Speed map of 1610, held in various archival collections, remains the clearest evidence of what Careios Hospital actually looked like and where it stood.