The Orient Express ran as a scheduled service from 1865 to 2009 (the current version is run by a private company as an 'experience trip' from London to Venice). It has taken five different routes over the years, and only 1 city has been a stop on all five routes - which one?
I took a version of the Orient Express from Milan to Istanbul and back (well not quite, lack of planning re Bulgarian visa led to unscheduled stop in Belgrade and emergency flight to Istanbul from there on the way out), 2nd class, in 1989. Not a glamourous experience at all, I've had more comfortable train rides in India and China at a fraction of the cost. Least comfortable of all though Mandalay to Rangoon in Burma in a train which had, for some reason, oval wheels.