Prudish, puritanical Americans are sometimes shocked by the... openness of the French.  Posters such as these would never survive in an American subway system... if they were permitted to be put up in the first place. 

The poster above advertises a museum exhibit focusing on the lavish night club shows of the 20s and 30s.  The topless woman shown is Josephine Baker, an American entertainer who was a sensation in Paris in the 30s. 

As if to shock the unwary even more...  "Elle avait de tout petits tetons" (She has nice little bumps). 

"Samaritaine" is one of Paris' upscale department stores, but they have sales just like every other department store you've ever seen.  Note the wall where the two people are passing: it has three maps, from left to right: (1) a map of the area around this station, (2) a standard Metro map, and (3) a street-level map of Paris showing street names and the actual locations of all the Metro stations.  If you can't find your way around Paris on the Metro, you probably shouldn't be walking around unattended.