I have been to a grand total of 5 museums on my trip to Essen, Paris, and London. My absolute favorite was Musee Galliera. "Why?" You may ask. Because it is a fashion museum. I have never been to one before and I have truly found my happy place. I love it more than flea markets, baguettes, and the rest of the other trappings of Paris.
Les Annees 50s is an exhibit spanning the years 1947-1957, featuring clothing by French couturiers such as Christian Dior, Jacques Fath, Mme. Gres, Gabrielle Chanel, and more. It even had the iconic Dior bar suit from his a/h 1947 (New Look) collection. It also has accessories, magazine covers, and sewing patterns from that era. And... they are screening movies of that period too! It is the best and if you are in Paris in the next month or so (or live in Paris) you need to go see it!
(Pictures via vogue.fr, because cameras are not allowed.)