Photo: Old Paris Metro Map (Detail), c. 1969-1977
This is simply gorgeous. The fact that the RER terminates at Nation dates this map from between 1969 (when the RATP first purchased the line from the SNCF) and 1977 (when the line was extended through Paris and became the RER “A” line we know today). The original post on Flickr does not note where this map is (or was) located. Source: lionelofparis/Flickr