There was a story on the BBC a couple weeks back marking the 125th anniversary of the Greenwich Meridian. Seems strange now, in the age of GPS, to think that there was a time when nobody could agree on the world's lines of longitude.
Quote from the story: "The world was in a very big mix-up," explains Dr Avraham Ariel, author of Plotting the Globe. "People had lots of prime meridians. Earlier in Europe there were 20 prime meridians. The Russians had two or three, the Spanish had their own and so on."
Which, of course, was one of the key plot points in Red Rackham's Treasure...