Patek Philippe Perpetual Calendar Cervo Eterna’s watches have had a

Eterna’s watches have had a history of being taken to some of the most forbidding environments—such as Thor Heyerdahl’s three-month voyage across the Pacific in a balsa wood raft

it’s accompanied by its factory goodies

and comes fitted to a correct stainless steel multi-link bracelet with signed locking clasp

Every unique case line and dial trait that makes the Royal Oak one of the most instantly recognizable watches ever made is highlighted in this 1974 ad in a washed gray-brown tone — the octagonal bezel with its signature screws

Its distinctive Art Deco styling is a product of its era

Patek Philippe Perpetual Calendar Cervo Eterna’s watches have had aA perpetual calendar is like a small computer on your wrist. Think of it this way: Imagine a watch that keeps track of not only the time, but also the date, the day of the week, and the month, and also tells you whether it's a leap year or not, and what the current phase of the moon is. Oh, and one more thing imagine it does all of this mechanically, using springs and gears, and that you only have to adjust it once every century or so. Crazy, right?