Châtelet is a station of the Paris Métro and Île-de-France's RER commuter rail service, located in the centre of medieval Paris, on the border between the 1st and 4th arrondissements. It serves RER A, RER B and RER D, as well as Line 1, Line 4, Line 7, Line 11 and Line 14 of the Paris Métro; it is the southern terminus of Line 11. The station is made up of two parts connected by a long corridor: Lines 7 and 11 under the Place du Châtelet and the Quai de Gesvre, next to the Seine; Lines 1, 4 and 14 towards Rue Saint-Denis and the Rue de Rivoli.

The Paris Métro, operated by the Régie autonome des transports parisiens (RATP), is a rapid transit system in the Paris metropolitan area, France. A symbol of the city, it is known for its density within the capital's territorial limits, uniform architecture and unique historical entrances influenced by Art Nouveau. The system is 226.9 kilometres (141.0 mi) long, mostly underground. It has 308 stations of which 64 have transfers between lines. There are 16 lines, numbered 1 to 14, with two lines, Line 3bis and Line 7bis, named because they used to be part of Line 3 and Line 7, respectively. Line 1, Line 4 and Line 14 are automated. Lines are identified on maps by number and colour, with the direction of travel indicated by the terminus.