Because of the enormous cost of these two lines, the third planned line was abandoned and the authorities decided that later developments of the RER network would be more cheaply developed by the SNCF, alongside its continued management of other suburban lines. However, the RER developed by the SNCF would never match the success of the RATP's two RER lines. In 1979, the SNCF developed Line C by joining the suburban lines of the Gare d'Austerlitz and Gare d'Orsay, the latter being converted into a museum dedicated to impressionist paintings. During the 1980s, it developed Line D, which was the second line planned by the initial RER schedule, but serving Châtelet instead of République to reduce costs. A huge Métro-RER hub was created at Châtelet–Les Halles, becoming one of the world's largest underground stations.