Somerset House (built 1769–70; demolished 1915), was an 18th-century town house on the east side of Park Lane, where it meets Oxford Street, in the Mayfair area of London. It was also known as 40 Park Lane, although a renumbering means that the site is now called 140 Park Lane.
The freehold of the house was always with the Grosvenor family, while the successive owners of the lease were the 2nd Viscount Bateman, followed by Warren Hastings, a former Governor-General of India, the third Earl of Rosebery, the Dukes of Somerset, after whom the house took its longest-surviving name, and finally the publisher George Murray Smith and his widow.