The interiors of the building are the finest in Wales of their period, and particularly in the formal public areas are almost unaltered. NE block (surmounted by tower) contains council suites. Entrance foyer (full height of building) faced with stone, vaulted gilded coffered ceiling, floors in travertine with green marble patterning. To each side bronze gates (Egyptian style) to stairs down to lower ground floor with Rates Hall with plaster roundels of coins minted in Wales. Grand staircase (gilded coffered ceiling, and bronze handrails with viking ships’ prows) up to grand corridor (stone doorcases with grotesque heads to L and R) and portal to Antechamber in Roman Doric style, coffered barrel-vaulted ceiling; to ends, entrances to reception room (L) and robing room (R) have arches with inset columns and entableture bearing urns, lunettes over; portal to lobby of council chamber. Lobby connects to Council Chamber, top lit , with fluted Ionic columns in Australian walnut (at time of construction at circa 7m largest ever built); Australian walnut panelling to walls with ebony banding; tapestry frieze above panelling represents Gorsedd procession. Horseshoe benches (Australian walnut), upholstered seating with Swansea arms; enclosure to mayoral seat backed by screen with pediment; in centre of horseshoe, table and upholstered chairs; public/press benches to rear. Fittings include original lighting, and gilt bronze fittings with Welsh symbols e.g. Leek, and goat on radiator grilles. Reception Room has minstrels gallery with railings in form of music stave, with notes and violin bows, Doric columns to main doorway, classicising doors with Art Deco type door furniture; panelling with cross-banding; Robing room has fitted lockers in walnut panelling. Grand corridor has coffered barrel vaulted ceiling, travertine and marble floor, classicising doorcases, heraldic shields of Swansea families; corridor flanked by offices and committee rooms with walnut panelling and screens, art deco chimneypieces, original tables and chairs. SE Block has councillor’s library, and corridor to George Hall with coffered ceiling, broad fluted pilasters, palmette frieze, reliefs of tragic and comic masks and of drama through the ages e.g. Commedia dell’arte, C16 and C17 theatre scenes.
George Hall connects via tunnel vaulted corridor with Adamesque fanlights to end walls to Brangwyn Hall, large rectangular concert hall (approx 49m x 19m x 13.5m), deeply coffered ceiling with original polygonal bronze and glass light fittings; broad fluted pilasters, panelled frieze band; rectangular clerestorey windows. Walls faced with acoustic tiles simulating Portland stone and have walnut-panelled dado. Walls hung with the Brangwyn Panels, 18 paintings up to 6m x 4m in size, depicting nations and people, flora and fauna of the British Empire. Deep stage/concert platform has large gilt bronze grilles to organ pipework. Entrance lobby of Brangwyn Hall has groined vault to ceiling (tympana to ends with relief decoration), floor in travertine and marble, classicising architraves to doors; two polygonal bronze booths, bronze inner doors. Corridor on 3 sides of hall; artists’ rooms to rear of stage.
SW block comprises Law Courts; two courtrooms (civil and criminal) aligned side-by-side; top lit, simple classicising details, coffered ceiling, panelled frieze, lunette windows to outer walls, public galleries to SW. Assize Hall has coffered barrel-vaulted ceiling (original polygonal bronze and glass light fittings); 2 bridges to public galleries carried on 4 Greek Doric columns, lunette with large low-relief of early law-giving in Wales; corridors with offices to outer walls of court block.
NW block is municipal offices with central corridors flanked by offices; simple classical details.