Time-zone function The International Meridian Conference decided on a common time-zone system in 1884, splitting the earth into 24 time zones. However, the victory march of watches with time zone displays only began in the 20th century when aeroplanes enabled rapid travel across different time zones.

The time-zone models from A. Lange & Söhne are the perfect accoutrements for any globetrotter. They let wearers see the time where they are currently staying and the time at home, all at a single glance. There is a button for setting the local time with ease. 

This picture illustrates the intricate time zone mechanism