On 8 October 1792 the young merchant Wilhelm Mülhens married his sweetheart. As a wedding present a Carthusian monk gave the couple a simple gift in the form of a recipe for the production of a miracle water, the perfume we now know as Eau de Cologne. Mülhens built a factory for producing the perfume, which is believed to have magical healing qualities and that was originally swallowed as well as applied externally, on Cologne's Glockengasse. In 1796 during the French occupation of Cologne the city commander General Daurier ordered that all addresses in the city were to be changed. Mülhens' factory got the number 4711, and thanks to some clever early marketing his perfume became a world leader. The building now houses a 4711 shop and museum. High up on the wall overlooking the opera is an elaborate clock with models of French soldiers and horses that plays the Marseillaise on the hour from 09:00 to 19:00. For more extensive information about Cologne's most famous product, have a look at the 4711 website.