Marchmont House was built in 1754 for Hugh Hume, the 3rd (and last) Earl of Marchmont (1708-94), by Thomas Gibson, although it is often mistakenly attributed to William Adam. Replacing the nearby Redbraes Castle, of which little now remains, Marchmont is located a mile (1.5 km) south of Polwarth in the Scottish Borders. This fine country house comprises two floors and a basement level, and has been renovated and remodelled by architects such as William Burn (1834) and Sir Robert Lorimer (1913-20). Notable features include the ornamental plasterwork in its hallway, the mahogany-panelled library and the oak panelling in the music room, which also features a full-size organ installed in 1914. The rococo plasterwork in the Drawing Room represents the bounty of nature and the seasons, while the Dining Room is decorated in a more restrained Neo-Georgian style, having been remodelled by Lorimer. The principal rooms all feature particularly fine chimney-pieces.
The house was acquired from the Hume family by the advocate Robert Finnie McEwen in 1913 and passed to Sue Ryder Care on the death of Sir James McEwen in 1983, aged only 23. It opened as a care centre for young sick and disabled people in 1989. Marchmont sits amongst extensive gardens and policies, which although now a little tired was once one of the finest designed landscapes in Scotland. A vista extends through an avenue of trees to Marchmont Doo'cot 1½ miles (2.5 km) to the northeast.