Kensington Gardens, once the private gardens of Kensington Palace, is one of the Royal Parks of London, lying immediately to the west of Hyde Park. Most of it is in the City of Westminster, but a small section to the west is in the Royal Borough of Kensington and Chelsea. It covers 275 acres (1.1 km²). The open spaces of Kensington Gardens, Hyde Park, Green Park and St. James's Park together form an almost continuous "green lung" in the heart of London between Kensington and Westminster.