54, 56, 58, 58A Castle Street, Edinburgh

These are a pair of former houses, now flats, built between 1792 and 1794 on Castle Street, Edinburgh. They are a prominent three-storey and attic structure, originally designed as a pair of houses but later converted into flats. The facades are constructed of polished cream sandstone ashlar, with rusticated detailing at ground level. A cill course runs along the first and second floors, and there is an eaves cornice. The central bay features a doorway leading to a common stair, with a six-pane fanlight above. This is flanked by Roman Doric doorpieces with tripartite pilasters and plate glass fanlights. The outer bays are united as single, full-height bowed fronts, with rustication at ground level; No. 58's ground level has been built out. At the first floor, all windows have been lowered, except for the one above the common stair. No. 54 has fine cast-iron balconies with an anthemion design dating from the 1820s. Dormers, dating from the earlier 19th century, are positioned on the roof, paired to the north and single to the south, with additional rooflights.

The rear elevation is of irregular coursed rubble, with the central two bays slightly projecting, and a central closet tower. The windows are 12-pane timber sash and case, with 15 panes at the first floor. The roof has ashlar coped skews, ashlar stacks at the centre, a rebuilt stone stack to the south, and a rendered stack to the north. Grey slates cover the roof.

The interior of No. 54 features a grand archway leading to a large, open central stairhall. A curving cantilevered stone stair begins on axis and curves to the right, with a swagged frieze at the landing. The former dining room retains a panelled dado, pilasters to the windows, a simple sideboard recess, and a chimneypiece. The former drawing room has an apsidal end, balanced by the bow, with double doors leading to the rear, panelled pilasters to the windows, and a simple chimneypiece. No. 58 has an archway in the entrance hall with a glazed screen. It also features a similar open stairhall, with a completely open cantilevered stair extended up to the attic and large open landings. The stair has plain, square iron banisters. Some original plasterwork remains in No. 54 at ground level. The former dining room and northwest room in No. 54 have been incorporated into a restaurant (No. 58a). The first floor of No. 58 includes a niche in the landing, a plate glass screen to the front lobby, and an apsidal-ended former drawing room with panelled pilasters to the windows and a Grecian marble chimneypiece with a reeded frieze and pilasters. The second floor (a former flat) has a sideboard recess in the front room and a chimneypiece with black and orange veined marble.

Cast-iron spearhead railings are present.