The 1950s and 1960s ushered in a new era of travel; as commercial flight became widely available, people could easily travel through multiple time zones in one day. With this easy travel, brands began developing watches to accommodate the time changes, perhaps most famously the Rolex GMT. In 1959, Patek Philippe patented the Time Zone Watch system which is used in this Travel Time Ref. 2597. This reference is the classic ref. 570 case, with a travel time movement and two push buttons on the left side of the case. The top button advances the hour hand forward, while the bottom button moves it back and hour. These watches are exceptionally rare and perhaps the most elegant travel time watch in history.