— Line 7, coloured brown (currently known as Plaça Catalunya - Avinguda Tibidabo), is a metro-like commuter train line in the Barcelona Metro network operated by FGC, and part of the ATM fare-integrated transport system. Also known as Línia de Balmes, as it climbs Carrer de Balmes uphill into Tibidabo, it shares three stations with FGC L6. A more effective integration into the main metro system is expected to be applied, as well as an extension of the line.
When the city government was to extend the Balmes street north of the Travessera de Gràcia street it also considered the option of building a tunnel under the street. The idea was that the Barcelona-Sarria railway company would use the tunnel, construction started at the end of 1921 without any agreement over the use of the tunnel. The construction of this 1,9 km tunnel was built with cut and cover and the works would last for about 8 years. In 1929 the Balmes street tunnel including the four stations Plaça Molina, Pàdua, Mercado (later El Putxet) and Av. Tibidabo was officially finalized of which the station Padua was only partially built as the area it would serve was not yet urbanized.
The same year Barcelona-Sarria railway line had been rebuilt as an underground line and at the same time connected to the Balmes street tunnel. However, only in the 1940s construction of housing along the Balmes street began so the tunnel and its stations remained unused. Only in 1950 the decision was taken to put the tunnel and its station into use. The stations which were originally inadequately built had to be expanded with new entrances and ticket halls so the line was only put into service in at the end of 1953, 32 years after the construction of it began.
During the Spanish Civil War, the tunnel was divided into 4 sections separated by heavy steel doors and adapted for the used as a storage facility for munition.