The London Bus is one of London's principal icons, the archetypal red rear-entrance double-deck Routemaster being recognised worldwide. Although the Routemaster has now been largely phased out of service, with only two heritage routes still using the vehicles, the majority of buses in London are still red and therefore the red bus remains an iconic symbol of the city. A double-decker bus is a bus that has two storeys or 'decks'. While double-decker long-distance coaches are in widespread use around the world, double-decker city buses are less common. Double-decker buses are popular in some cities of Europe and in parts of Asia, usually in former British colonies (Hong Kong, Singapore etc.) Some double-deckers specialise in short sight-seeing tours for tourists for, as William Ewart Gladstone observed, "the way to see London is from the top of a 'bus".