Orient Express

The Orient Express was a long-distance passenger train originally operated by the Compagnie Internationale des Wagons-Lits on Earth. One Orient Express was built that travelled in space.

History
The two city names most intimately associated with the Orient Express were Paris and Istanbul, the original endpoints of the service. In 1887, Sherlock Holmes and Dr. Watson were riding on the Express through Austria when they were stopped by the train of Pope Leo XIII, who commissioned Holmes to investigate the disappearance of books from the Library of St John the Beheaded in London. (PROSE: All-Consuming Fire)

A space-faring version of the train was built that attempted to mimic the original in fine detail. (TV: Mummy on the Orient Express)

Also Briefly Referenced at the end of Season 5 Episode 13. However which version is unknown. (TV: The Big Bang)