You want to see how Paris was created, from the small city of the Middle Ages up to today? What were the town plans of each century or decade? The Pavillon de l’Arsenal is all that. From the beginning of the city up to today, the walls are full of maps, pictures, drawings and photos of the city.
The walls are not only covered with information about the construction of Paris, it also speaks about the suburbs, explaining how the government decided to promote building and renting out at moderate rates in the suburbs or the emergence of the suburban area.
If you are into urbanism and town planning this is a pretty interesting place to go to.
Check their website, between exhibitions and talks they have a very interesting agenda.