The most expensive piano ever sold at auction was the Casablanca (1943) piano, otherwise known as the ‘As Time Goes By’ piano – the one that Dooley Wilson’s Sam was playing on when Ingrid Bergman uttered one of Hollywood’s most famous lines: ‘Play it, Sam, Play “As Time Goes By.”’ It is a symbolic part of one of the greatest love films of all time. It sold for $3.4 million to an anonymous buyer at Bonham’s Auction House in New York in 2014, complete with a photograph signed by Humphrey Bogart and a piece of chewing gum stuck under the keyboard. Dr Milan, the piano's previous owner, said that he had tried to ascertain whether the gum was Dooley Wilson's, but was unable to do so since nobody had Wilson's fingerprints. It was probably made in 1927 by the First National Pictures studio, which later merged with Warner Brothers. Unlike most pianos that have 88 keys, this upright, wooden piano only has 58. It is golden yellow, with an intricate design of Moroccan green and gold, though of course in the movie you wouldn’t be able to tell, given that it’s black and white.