It occurs to me looking at the map that a tourist in modern day Paris would still be well-served by this network.

That thought also made me wonder how central Paris' modern metro system overlays onto this. Here's a quick little visualization: https://stirring-biscotti-a978fa.netlify.app/

If you're traveling to or interested in Paris and its history, I really enjoyed "Parisians: An Adventure History of Paris" by Graham Robb. Has some good, accessible and entertaining history relating to (among other things) the construction of the metro.