It was in 1850 that Marlborough House was settled upon the Prince of Wales, and since his Royal Highness's marriage, in 1863, it has been his town house. Situated on the south side of Pall Mall, next St. James's Palace, the house was built in 1710 by Wren for the first Duke of Marlborough, whose wife Sarah declared that the concession of this splendid site was almost the only boon she obtained from Queen Anne. In 1817 the Government bought Marlborough House for Princess Charlotte and her husband, Prince Leopold of Saxe-Coburg, and subsequently it was given to Queen Adelaide as a Dowager house; while after her death the Vernon pictures were kept here. It is a red-brick building with stone facings. Our view shows the front looking towards the Mall.
source: The Queen's London : a Pictorial and Descriptive Record of the Streets, Buildings, Parks and Scenery of the Great Metropolis, 1896