Credit for inventing eau de cologne is usually given to Johann Maria Farina and dated to 1709. This private museum in the original factory building takes you on a 'scent'-sory journey through 300 years of perfume making. It can be visited on guided 45-minute tours (some in English) offered on the hour.
There's also a huge shop. Tickets can be bought online.
Early fans of eau de cologne reportedly included France's King Louis XV and Prussia's King Frederick the Great.