Here's a link to a new museum which opened this summer in the 14th arrondissement. Permanent collection is free and excellent, but you have to pay to visit the underground bunker (part of the Catacombs), which was headquarters for the liberation of Paris and is a steep 100 stair descent.
http://www.museeliberation-leclerc-moulin.paris.fr/en/visit-museum/useful-information
Should be interesting- Thank you.
Nice -- except for the 100 stairs to the underground command post. But they say there's a 360° virtual tour that's handicapped accessible.