It is disused now, its elaborate arrangement of interconnected ranges and additions quietly deteriorating, though the bones of its original form remain legible to anyone who looks carefully.

The building dates to around 1730 and was designed by Thomas Burgh, the Surveyor General of Ireland who was also responsible for the nearby Dr Steevens's Hospital and for Trinity College Dublin's great library. Burgh was the dominant figure in early eighteenth-century Irish institutional architecture, and this infirmary represents another strand of his output, one tied directly to the Royal Hospital Kilmainham, Ireland's first classical building and a home for veteran soldiers modelled loosely on Les Invalides in Paris. The infirmary sat outside the main hospital wall, as noted by the writer John Dunton, who recorded in the late seventeenth century that it was positioned nearer to the river and that the steward of the hospital and his family also lived within it. The National Inventory of Architectural Heritage records the building in some detail: a two-storey, five-bay main block with a breakfront to the west elevation, connected by a lower single-bay link to a six-bay recessed block to the south, with a two-bay gable-fronted addition to the south block's front and a single-storey three-bay range running perpendicular to the main ranges. Multiple later extensions were added to the rear. Together with the Royal Hospital and Dr Steevens's Hospital nearby, it formed part of a concentrated group of early Dublin institutional buildings.

The infirmary sits off Military Road near the Saint John's Road junction in Dublin 8, in the shadow of the far better-known Royal Hospital, which today houses the Irish Museum of Modern Art. Because the infirmary is disused and not publicly accessible, it is best appreciated from the road, where the west elevation and its gable-fronted addition give a reasonable sense of the original composition. Visitors to the Royal Hospital grounds will find the building just outside the perimeter, its plainness and evident neglect making a quiet contrast with the grandeur of its neighbour. The NIAH register entry, number 50080082, provides the most thorough accessible record of its current architectural condition.