The house is best known for its important art collection, which includes works by Vermeer, Van Dyck, Hals, Gainsborough and Turner.
The original house dates from the early 17th century, the orangery having been added in about 1700. In 1754 it was bought by William Murray, 1st Earl of Mansfield, who commissioned Robert Adam to remodel it. The library has become one of the designer's most famous interiors, described by his contemporaries as 'superior to anything of the kind in England'.
In 1793-6 George Saunders added two wings on the north side containing offices, kitchen buildings and a brewery. While under the ownership of the 2nd Earl and Countess of Mansfield the estate was extended again with a new dairy to supply Kenwood House with milk and cheese.
Lord Iveagh, a member of the Guinness family, bought the house from the Mansfield family in 1925 but never got to live in it as he died just two years later. Thanks to the Iveagh Bequest, Kenwood was donated to the nation, its text stipulating that it should be opened to the public free of charge, with the 'mansion and its content... preserved as a fine example of the artistic home of a gentleman of the 18th century'. Unfortunately the house's contents had already been sold by then, so 18th-century furniture has since been added.
In 2012–13 Kenwood House underwent an extensive £5.95m repair and restoration programme. Over 400 paint samples were analysed in order to return Robert Adam's iconic library to its original colour palette, which combines blues, pinks and whites.
The project involved the room's gilded ceiling being 'reversibly painted over' in white, after research suggested that the gold was not part of the original design and had been added sometime later. Three other rooms – the entrance hall, great stairs, antechamber – also received sympathetic restoration, while four rooms were redecorated in 18th-century style, the painting collection was rehung, and the house's slate roof was repaired.
Lord Iveagh was a prolific collector of Old Master and British paintings, which were donated to the nation as part of the Iveagh Bequest in 1929. This collection of 63 works includes prominent pieces by Joshua Reynolds, Pieter van den Broecke and Thomas Gainsborough, as well as The Guitar Player by Johannes Vermeer and Self Portrait with Two Circles, a late work of Rembrandt's.
In recent years the gardens surrounding the house have been furnished with sculptures by Barbara Hepworth, Henry Moore and Eugène Dodeigne.