Part of Royal Institution

No 20 is a terrace house that dates from the late 18th century and was remodeled internally in the early and late 19th century. It is constructed of yellow stock brick and has a slate roof. The building has four storeys, a basement, and a dormered mansard roof, and it is five windows wide. The ground floor has been altered to include a three-bay shop front from the early to mid-20th century, along with a semicircular arched doorway to the right that features a fanlight, all set within a stucco surround with consoles supporting an entablature. The upper floors have sash windows without glazing bars, which are set under flat gauged arches. There is a moulded stone cornice above the second floor and a parapet with coping. The area is enclosed by cast iron railings topped with urn finials. Inside, the early 19th-century features include cornices, doorcases, a stone staircase with a wrought iron balustrade, and a chimneypiece that has a Wedgwood plaque originally from No 32 Soho Square, the house of Sir Joseph Banks. No 20 was incorporated into the Royal Institution in 1894.