For decades, the Calatrava – the prototype of the classic round wristwatch, including its Officer's- style variations with dust covers over the case back – has ranked among the most iconic creations of Patek Philippe. Uniting the key characteristics of this watch family, the new Calatrava Ref. 5227 now features a display back protected with a separate dust cover. The special twist: The entire hinge is on the inside of the cover, making it invisible even to the connoisseur…

Like most machines, a mechanical watch movement involves four basic operations: energy is generated, stored, transmitted and regulated. For centuries, these constants of mechanical watchmaking have been performed by three complementary blocks: a power storage system with cylindrical barrel, a transmission system with pinions and gears, and a regulation system with balance wheel, spiral hairspring and escapement.

Now, to mark its 150th anniversary, TAG Heuer proudly introduces the TAG Heuer Pendulum Concept, the first-ever mechanical movement without hairspring…