"The map of Cassini or map of the Academy is the first topographic and geometric map established of the Kingdom of France as a whole. The map was for the time a real innovation and a decisive technical advance. It is the first map to be based on a geodesic triangulation. Four generations of the Cassini carried out the work."
This map is impressively detailed and accurate. When you look at a small village-sized area that you know today, you can often recognize the features on the Cassini map (no always though ; many hills were drawn as they appeared from afar, many of the tiniest locations were marked upon hearing word of them by locals).
But it gets even more impressive when you know what the times were like when this map was made.
Neighbouring valleys hosted different languages that sometimes were not intelligible to each other.
In places, local people didn't have a name for the prominent mountain they grew up and spent their life under.
One of Cassini's young cartographers was notoriously killed by villagers who put an axe in his head, because pointing his mysterious brass and glass instruments at mountains and bell towers made them be sure he was a bad wizard.
Those were the times. And this is the map !
I work with several professional cartographers here in France. All of them have several large printed maps in their offices, just for the beauty of them. I don't know of one who does not have a Cassini map along, somewhere on an office wall.
"The map of Cassini or map of the Academy is the first topographic and geometric map established of the Kingdom of France as a whole. The map was for the time a real innovation and a decisive technical advance. It is the first map to be based on a geodesic triangulation. Four generations of the Cassini carried out the work."
https://en.wikipedia.org/wiki/Cassini_map