Marco Polo is the completely missing fourth serial in the British science fiction television series Doctor Who, which was first broadcast in seven weekly parts from 22 February to 4 April 1964. The story is set in China, in the year 1289, with the regular series characters interacting with Venetian merchant-explorer Marco Polo and Mongolian Emperor Kublai Khan. The historical period and context avoids science fiction elements beyond establishing the way by which the Doctor and his companions have travelled to the past. Although audio recordings and still photographs of the story exist, no footage of this serial is known to have survived.