17-21, Portland Place W1

Nos. 17 to 21 on Portland Place are large terraced townhouses built between 1776 and around 1780 by James Adam, along with his brothers and John Elwes, as part of a speculative development on a Portland Estate lease. The houses are constructed of stock brick with channelled or rusticated stucco ground floors and feature slate roofs. Nos. 17 and 19 have astylar fronts, while No. 21, the central house of the originally symmetrical block, is distinguished by a giant pilaster order and a pediment.

The buildings rise four storeys, including an added attic storey, and have dormered mansards on Nos. 17 and 19, with basements beneath. Each house has a three-window wide front. The doorways are semicircular arched, with No. 17 featuring an entrance under a later Corinthian columned stucco porch on the Duchess Street side, and No. 21 having an added Greek Doric columned stucco porch. The doors are panelled, with sidelights and fanlights in a Venetian window style. The upper floors have recessed sashes under flat gauged arches, while the ground floor windows of No. 21 are set in shallow arched panels.

The ground floor stuccowork is finished with a plat band, and there is a moulded stucco band over the first floor, with a main stucco entablature over the second floor. Nos. 17 and 19 have an attic cornice with a balustraded parapet, while No. 21 features Ionic pilasters on the first and third floors, with the attic divided by pilaster strips and topped with a crowning pediment and dentil cornice. Continuous early 19th-century cast iron balconies extend over the first floor porch of No. 21, and there are cast iron area railings with plumbed spike finials.

Nos. 17 and 21 retain many original features designed by Adam, including delicate plasterwork, stone geometrical staircases with wrought iron balustrades, statuary marble chimneypieces, and overmantel medallions.