During my last visit to Paris, my friend and I (at her suggestion) went to see the Madame Grès exhibit at the Musée Bourdelle. If you like looking at clothes, I highly recommend this visit to anyone who will be in Paris between now and July 24th.
Here's my brochure and entry ticket :)
The museum is dedicated to the sculptor Antoine Bourdelle, but works by Madame Grès are currently interspersed amongst Bourdelle's sculptures because the Galliera (the Paris fashion museum) is closed for renovations. Appropriately, before starting her design career, Madame Grès herself studied sculpture and kept that approach with regards to her sewing and design.
The museum looks rather small from the outside, but it's actually quite large so give yourself a hour and a half, at least. It's located in the 15th arrondissement, not far from Gare de Montparnasse. Here's a website about the exhibit (in French): Madame Grès.
On display are Madame Grès' works spanning her entire career, starting with the 1930s and ending with the 80s. She is chiefly known for her minutely pleated gowns that reinterpret Ancient Greek style. But don't be fooled, she doesn't only work with neutral tones! She had some eye-popping colors: bright greens, reds, oranges, etc. And during the 50s her style definitely became a little more rigid, à la Dior, yet (I feel) still retained her style.
I'm not going to try to explain who Madame Grès (otherwise known as Alix Barton) was - but you can read this article: Madame Grès. The Wikipedia entry is pitiful. I will simply mention that she designed the costumes for Jean Giraudoux's play La guerre de troie n'aura pas lieu and that you can see some of her sketches for that production as well. And they're awesome!
You can also see some photos of her work with a Google search. And if you're interested in her Vogue sewing patterns, you should check out Vintage Patterns, where she has her own category.