The title of the film refers to the Topkapi Palace built, by the Ottoman Sultan Mehmed II in 1459, after the fall of the Byzantine Empire.The Ottoman sultans made their main residence in the Topkapi palace for 400 years. It became a museum in 1924 and its hundreds of rooms contain numerous collections of historical and religious relics, treasures and jewelry. Topkapi means "Cannon Gate" in the Turkish language.
Eric Ambler's "The Light of Day" (1962), upon which this film 'based, is narrated by Arthur Simpson, the character played by Peter Ustinov in the film. Ambler also wrote a sequel, "Dirty Story" (1967), in which Arthur continues to relate his adventures, this time as a reluctant mercenary in Africa.