The Carmarthenshire Infirmary was built in 1857-8 by William Wesley Jenkins of London, the building work untaken by William Lewis for the accepted tender of £3260, with Thomas Charles of Llandeilo supervising the work. The foundation stone was laid by Bishop Connop Thirwall on the 14th May 1857, and it opened on the 1st July 1858. Between 1899 and 1934 extensions were added to the rear, and in 1948 it was taken over by the NHS. It closed in the later 20th century, and most of the rear extensions were demolished in 2002 pending conversion to offices or flats.

The building is two-storeyed and built in the Italinate style. The exterior is stuccoed with a hipped slate roof, and four rendered chimneys. The front elevation is of seven bays arranged 2-3-2, with banded pilasters between the sections which have paired brackets in place of capitals. The windows are 12-pane hornless sashes in moulded architraves, although the central window has been altered with a 5-light sash produced from originally a larger sash with a flat cornice. There is a broad sill band with 'Carmarthenshire Infirmary Supported by Voluntary Contributions' inscribed on it. A central doorway with a pedimented surround of Doric pilasters, frieze and dentilled pediment, the frieze carrying the inscription 'Founded 1858'. The end bays have three first floor windows, the central one of which is blind, then there is a recessed bay linking to a similar sized parallel rear range. This has a hipped slate roof, and the rear elevation has been altered by the later extensions.

the front block has been largely modernised internally, the main survival being a staircase with a continuous handrail and stick balusters together with a large tripartite sash stair window.

(Source; Cadw listing description) S Fielding RCAHMW 06/06/2005