A friend of my mother recently gave me this cologne as a gift. I really liked the fresh smell, and the wonderfully retro kitsch bottle, which reminded me of some old Versace perfumes (the jeans collection). After some research, (i.e. 5 minutes in wikipedia) I found out that it is indeed a historical cologne. Made in Germany and named after the number assigned to the residence of Wilhelm Mülhens, it has a quite interesting past. You can read more here
I also found out that it used to be considered "miracle water" because of claims that smelling it relieved headaches. Also, due to its high alcohol content violin players used it to clean the strings of their instruments. Hm.
It does smell nice though!