One of the most prestigious watch manufacturers founded by a French horologist is located where? 
Adrien Philippe: Jean Adrien Philippe (16 April 1815, La Bazoche-Gouet, Eure-et-Loir – 5 January 1894) was French horologist and cofounder of watchmaker Patek Philippe & Co. of Geneva, Switzerland. Patek Philippe &amp; Co.:  It is considered by many experts and aficionados to be one of the most prestigious watch manufacturers.
Geneva, Switzerland