Signage over the years.

I like this example of different generations of signage:  the still-visible  "advertisement" painted on the building's wall for Suze aperitif drink; and the newer generation of "graffiti".  All clearly visible to travelers in the Metro, or pedestrians and cars in the street.
This line 6 of the  Paris Metro was built in 1900 to 1906.  13,5 km long, of which 45% is "elevated" as here at the Sevres Lecourbe station.  There are wonderful views of Paris on this line, and in particular of the Eiffel Tower, where the metro line crosses over the Seine river.