Paris Métro Line 1 is one of the sixteen lines of the Paris Métro. It connects La Défense–Grande Arche in the northwest and Château de Vincennes in the southeast. With a length of 16.5 km (10.3 mi), it constitutes an important east–west transportation route within the City of Paris. Excluding RER commuter lines, it is the busiest line on the network with 181.2 million travellers in 2017 or 496,000 people per day on average.

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.