15, Portland Square

15 Portland Square is a late 19th-century house, dated 1881, that has been converted into offices. It is constructed of calciferous sandstone ashlar, set on a moulded plinth, and features an eaves cornice. The roof is a Mansard design, covered with greenslate and incorporating original wooden gabled dormers alongside later, 20th-century boxed dormers and roof-apex railings. Rear chimney stacks are of ashlar construction.

The building is two and a half storeys high, with a basement, and has a double-depth plan laid out over three bays, with a five-bay return on Alfred Street South forming an overall L-shape. The central entrance features a round-arched porch with fluted pilasters, a frieze, and quatrefoil panels, housing a panelled door and fanlight. Flanking the entrance are squared bay windows, with mullioned and transomed sections of three lights, and two lights above the entrance. The return elevation has a squared bay window to the right, alongside a full-height stair window and single two- and three-light mullioned and transomed windows, all set beneath hoodmoulds.

The interior retains some panelled doors, moulded plaster ceiling cornices, and a wooden staircase with turned and fretted balusters, carved newel posts, and segmental plaster hall arches. Windows in the principal rooms are set within fluted wooden pilasters.