The first métro line in Paris was opened for the 1900 world fair. It ran from Porte de Vincennes on the eastern city limits to Porte Maillot on the western end and linked the different sites of the world fair as well as the Olympic games sites in the Bois de Vincennes. Today, it runs as far west as the La Défense business district which is outside the city limits.

Line 1 runs pretty much straight east-west on the historic axis of Paris, including the Avenue des Champs Élysées.

It crosses every other metro line except for the 3 and the 10 and is the most used, both by locals and by tourists, serving notably the Louvre, the Arc de Triomphe, and the Champs Élysées.

Built in part under the open sky, notably under the rue de Rivoli and the Champs Élysées, the corresponding stations are boxes the width of the street. Their walls are practically on the same level as the foundations of the buildings above.

The boxes were covered with a roof, as above at the Hôtel de Ville station with steel bars and rivets.

When the metro trains were lengthened from 5 to 6 cars, the platforms had to be extended as well, from 75 to 90m. In stations with fewer passengers, they simply dug into the tunnels, as at the far end of Saint Paul station below.

Since 2013, the line 1 is entirely automatic. In order to avoid any accidents or suicide attempts, all stations have glass walls along the entire length of the platform. There is no driver and you can stand at the head of the train. Let me take you on a ride.