Royal Commission on Ancient & Historical Monuments in Wales

The Royal Commission on Ancient & Historical Monuments in Wales is a three-storey building with a basement and attic, featuring a two-bay stucco front that is rusticated except for the second floor. It has a renewed slate roof with wide bracket eaves and red brick chimney stacks, along with slate-hung tunnel-roofed dormers. The building includes horned sash glazing and full-height splayed bat windows that have an unusual squeezed appearance, lacking the central window in each bay. To the right, there is a large Ionic doorcase with a cornice over a deep plain entablature, leading to modern boarded doors. A tripartite sash window is located in the basement. On the left side, there is an Egyptian-inspired doorcase leading to a side passage, with a rusticated parapet above an incised entablature supported by similarly detailed pilasters, featuring a keystone above a modern entrance.

The left side of the building has scribed cement render, while the rear elevation is constructed of rubble and features three windows with raised eaves, as indicated by joist sockets. There are two flat-roofed dormers, one louvred and the other sash glazed. The small pane sash windows below are mostly 16-pane, except for one fixed glazed window and one ground floor window that has marginal glazing bars and a Gothic stained glass traceried head. The basement includes French windows, and there is a modern cross-range extension.

Inside, the building retains fine early 19th-century details. The entrance hall features a panelled ceiling with beaded ribs and bosses, and an elliptical arch supported by fluted columns with heavily foliated capitals and ornamented spandrels, leading to a cantilevered oval well staircase. There are varied ornate cornices throughout the building, Regency doorcases, and some fireplaces with Egyptian-inspired details, along with panelled shutters for the bay windows. The main ground floor room has an interlace cornice and an ornate wide doorcase with double doors leading to the rear room, which has a full-width elaborate opening with two doorways and a central recess leading to a passage. The rear room features a Gothic window and an interlace foliage cornice similar to that of the main ground floor room. The first floor landing has a ribbed groin vault with arched openings to panelled doors, two of which are diagonally set.