Gare de Denfert-Rochereau is a train station in Paris. It was one of the first stations of the French railway network, and is still in use as a station of Paris' RER line B.
Built from 1842 and opened on 7 June 1846, the station building had a circular shape as it possessed a rail loop. Indeed the station was the Parisian terminus of a line from Sceaux. This system, named "Arnoux" (after its inventor), was abandoned at the end of the 19th century as it required the construction of specific engines capable of travelling on very tight curves and broad gauge tracks of 1.75 m (5 ft 8⁄8 in).
The line was extended to the Gare du Luxembourg in 1895, with the newly-created Port-Royal station along the way. The line was operated by the Chemin de Fer de Paris à Orléans until 1937 when the Compagnie du Chemin de Fer Métropolitain de Paris (CMP) (predecessor of the RATP) took over. It became line B of the RER in 1977 on being extended to meet line A at Châtelet - Les Halles.
The station building of Denfert-Rochereau station is the oldest railway building still standing in Paris.
Denfert-Rochereau remains a station of line B of the réseau express régional and is an interchange with the métro station of the same name, Station Denfert-Rochereau.