Their original London residence was on Millbank, but after the family had developed their Mayfair estates, they moved to Park Lane to build a house worthy of their wealth, status and influence in the 19th century.
Another extension was added in 1842, in the form of a 110-foot (34 m) long classical-style colonnaded entrance screen on Upper Grosvenor Street.
Thomas Cundy, the architect of this vast house, then proposed a larger mansion to go all the way along to Park Street, extending all the way to 230 feet (70 m).
In 1870, Hugh Grosvenor, 3rd Marquess of Westminster (later the 1st Duke) commissioned Henry Clutton to add a porte-cochère to the north, and he had many of the state rooms redesigned.
Some of these were sold between the wars, but most remain in the other Grosvenor family homes, mainly their country seat - Eaton Hall in Cheshire.