My favorite building in Paris (Usine de la Société Urbaine D'Air Comprimé (SUDAC)) are now part of Frédéric Borel’s, Paris Val-de-Seine Architecture School.
Originally the building was used for producing Compressed Air. It was build in 1890 and is (was) one of the most beautiful industrial relics in Paris.
I really don't like the new building by Frédéric Borel, which has been added to the old factory. If you ask me, it's a waste of space.