20 King Street

20 King Street is a house and shops that is taller than the adjoining properties at Nos 19 and 21. It features painted stucco with a slate close-eaved roof and no chimneys. The building has three bays and three storeys, with a stone plaque in the top right corner that is eroded but appears to be dated 1806. It has early 19th-century fluted metal rainwater heads, possibly lead, along with a lead downpipe. The upper floors have tripartite plate-glass sash windows, with the outer top floor windows and the first floor left window featuring cast-iron flower balconies from the late 19th century on their sills.

On the ground floor, there are two late 19th-century shops, each with a plate glass shop window that includes outer panelled pilasters and scrolled brackets carved with grotesque faces, along with a fascia and cornice above. The shop windows are canted in, with shop doors, and there is a recessed centre half-glazed double door that leads to the stairs for the upper floors. Inside, there are two iron columns in the shop windows marked "The Old Foundry Co, Carmarthen." The staircase to the upper floors features stick balusters around a small open well, with scrolled tread ends and a ramped rail.