A beautiful watch movement is engineered art – and like art, some examples are more prized than others. Among pre-1969 watches, the manually wound Valjoux 72 reigns. As the first modular movement – watchmakers could swap in their own parts to make it unique – it was used in such classics as the Heuer Carrera and the so-called Rolex Pre-Daytona. Other watch companies rolled their own movements: The Omega Caliber 321, Longines 13ZN, and Breguet Flyback all make vintage collectors' hearts flutter. In 1969 a group including Heuer, Breitling, and Hamilton co-created the first automatic chronograph movement (dubbed "Chronomatic" by Hamilton and Breitling; "Caliber 11" by Heuer). That same year Zenith debuted its own auto-chrono, the El Primero. All of these movements are both precise and highly desirable.