Identified by a large M in a circle, metro stations are easily spotted. The network of lines covers central Paris, and every station has clear indications, so you are unlikely to need help. Lines are identified by their end station, only two have branches, which means you have to check destination on the front of the train.
Doors open easily : lift the handle or press the button, and they shut automatically. Connections are called correspondances, and an orange sign on the platform indicates directions to your connecting line. Blue signs marked sortie indicate the exists.
One ticket is valid for every uninterrupted journey. After braving the automatic barriers, keep the ticket on you until you end your journey in case of inspectors.
Parisian public transportation is one of the best systems in the world. Metro maps are available free from any metro station and from some hotels.

Paris ComboPass® Lite provides 1 or 2-day pass packages that include free unlimited use of all the public transport services inside Paris and the inner suburbs (within 3 zones), free access to the Louvre with the 1-day pass and to the Orsay Museum with the 2-day version, a free Seine river cruise, special discounts and offers for additional Paris attractions, a free Paris street/metro/bus map, and 30 days access to online French lessons.

You can also see paris metro subway map.

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