Paris Métro Line 1 (French: "Ligne 1 du métro de Paris") 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 , it constitutes an important "East-West" transportation route for the City of Paris. Excluding RER () commuter lines, it is the most utilised line on the network with 181.2 million travellers in 2017 or 496,000 people per day on average.