Patek Philippe S.A. is a high-end Swiss watchmaking company which was established in 1839 as Patek, Czapek & Cie. by Antoine Norbert de Patek and François Czapek. In 1845, Czapek left the company and the firm was renamed Patek & Cie.. Adrien Philippe partnered with Patek in 1851 and the firm became Patek Philippe & Cie.. It's present name - Patek Philippe S.A. - was introduced when Charles and Jean Stern bought the prestigious company in 1932. The firm is still owned by the Stern family.
A very good video presentation on modern production methods of the factory:
A video on the Patek Museum: