Paris Metro Line 9
Paris Metro Line 9 is one of the sixteen lines of the Paris Métro network currently open. It links Pont de Sèvres in Boulogne-Billancourt, the third most populated city in Ile-de-France, to Mairie de Montreuil, the second most populated city of Seine-Saint-Denis in the east, along a parabolic - shaped route through the center of the French capital. With 133,24 million passengers in 2024, it is the third busiest line on the historic network, behind lines 1 and 4, as well as one of the longest. The first of the historic lines not part of Fulgence Bienvenüe's initial project, it is also the very first line of the Paris Métro to cross the borders of Paris and service its suburbs, with the line segment in Boulogne opening in 1934 following three years later by the segment in Montreuil. Since then, Line 9 didn't evolve much in terms of layout.