Breguet has an excellent museum above their Paris boutique. The museum is free, but you have to schedule an appointment.
My wife and I were on vacation in Paris two weeks ago, and we made it a point to visit. The collection ranges from the 1700's through the present day. I wouldn't consider myself a Breguet enthusiast, but seeing this collection gave me deep respect for the brand. I highly recommend this museum if you are interested in the history of watchmaking, and/or you want to see some incredible timepieces. Attached are some of my personal favorites from the collection.