Chang'an was an ancient capital of more than ten dynasties in chinese history, today known as xi'an. chang'an means "perpetual peace" in classical chinese since it was a capital that was repeatedly used by new chinese rulers. during the short-lived xin dynasty, the city was renamed "constant peace"
It was originally intended to shorten the sailing time between the Atlantic and Pacific Oceans. Were it not there, a ship would have to travel to the lowest tip of South America and back up again. It would extend any trip by not a trivial amount of time.
