Patek Philippe & Co. is a Swiss watch manufacturer founded in 1851, located in Geneva and the Vallée de Joux. It designs and manufactures timepieces and movements including some of the most complicated mechanical watches. It is considered by many experts and aficionados to be one of the most prestigious watch brands along with Audemars Piguet, Vacheron Constantin, and A. Lange & Söhne. Past owners of Patek Philippe watches include Pope Pius IX, Queen Victoria, Victor Emanuel III of Italy, Christian IX of Denmark. In 1851, Patek Philippe started supplying its watches to Queen Victoria and her consort, Prince Albert. Queen Victoria acquired a key-wound Patek Philippe watch created in a pendant style in November 1851 during the Great Exhibition of London.The queen owned one more exclusive Patek Philippe timepiece, to be worn pinned to clothing. This watch was suspended from a diamond and enamel brooch. Patek Philippe clientele has included Christian IX and Princess Louise of Denmark (the king and queen of Denmark), Victor Emmanuel III of Italy (king of Italy and Duke of Savoy), Hussein Kamel (Sultan of Egypt from 1914 to 1918). In 1989, Patek created one of the most complicated mechanical watches ever made, the Calibre 89, created for the 150th anniversary of the company. It holds 39 complications, including the date of Easter, time of sunrise, equation of time, sidereal time, and many other indicators. 1,728 unique parts allow sidereal time, a 2,800 star chart, and more.The Calibre 89 is also able to add a day to February for leap years while leaving out the extra day for every 100 year interval.