According to the official website, the Musée d'Orsay in Paris is renovating the Impressionist Gallery from 13 to 23 November 2018. Does someone know what that means? What does exactly the "Impressionist Gallery" refer to? Are the most famous artworks usually displayed in that room?
I visited the Musée d'Orsay in October of this year. It's a large museum with three floors of public exhibits wrapping around a central atrium. It's not the "Impressionist Gallery" it's the "Impressionist Galleries" (plural). It consists of several rooms on one side of the fifth floor. These are closed off, but a selection of the most famous impressionist pieces are are temporarily on exhibit on the other side of the fifth floor.
The other floors are mostly unaffected. My wife and I spent essentially all day there and certainly didn't see everything, despite the closure. If all you want to see is Cézanne, you might be disappointed, but if you are interested in Van Gough, Gaughin, Rodin, Lautrec, or anybody but the impressionists, there is plenty to see.
It means that the collection of Impressionist artworks normally on display in the gallery will not be accessible during the period stated. http://www.musee-orsay.fr/en/events/renovation-of-rooms.html There is a list of the works in the collection here https://en.wikipedia.org/wiki/Mus%C3%A9e_d%27Orsay