The Barcelona Metro or underground railway is probably the easiest and most convenient way of getting around the city for both tourists and residents alike.
The Metro System is run by two operators Transports Metroplolitans de Barcelona (TMB) run the majority of the network, whilst Ferrocarrils de la Generalitat de Catalunya (FGC) run Lines 6, 7 and 8.
The Metro serves the Barcelona Metropolitan area that comprises the City of Barcelona plus Sant Adrià de Besos, Santa Coloma de Gramenet, Badalona and Hospitalet de Llobregat,which are all in the comarca of El Barcelonès.
The network also extends south to towns in the Baix Llobregat such as Sant Boi and Cornellà.
You can buy single journey tickets and a variety of TMB travel cards, including the excellent value T10, in the machines in metro entrances.
If you are coming to Barcelona on vacation, it is well-worth investing in a three, four or five-day Barcelona Card, which not only gives full access to the Barcelona metro, buses, ferrocarrils, trams and funicular but also offers discounts in museums and sights as well as in restaurants and shops.
Metro Line 1 runs from Hospital de Bellvitge in Hospitalet to Fondo in Santa Coloma de Gramenet.
It is the most used line as it goes through important stations such as Catalunya, Espanya, Arc de Triomf and La Sagrera.
Metro Line 2 runs from Paral.lel in Barcelona city centre to the Pompeu Fabra University campus in Badalona.
The line was opened in 1995 and is useful for getting to Sant Adrià and Badalona as it has connections with the Red, Green/Yellow and Blue Lines at Universitat, Passeig de Gràcia and Sagrada Familia respectively.
Metro Line 3 runs from the University of Barcelona Zona Universitària at the end of Diagonal to Trinitat Nova. It opened in 1924 and is the oldest Barcelona Metro line.
It is another key line as it has stops at Sants-Estació, Catalunya and Diagonal.
Metro Line 4 runs from La Pau to Trinitat Nova and has important city centre stops at Verdaguer, Passeig de Gràcia and Urqinaona.
You're likely to use it quite a lot as Jaume I - the main stop for the Barri Gòtic is on the Yellow Line, as are Barceloneta, Vila Olímpica and the Forum.
Metro Line 5 runs from Cornellà Centre south of the city to Barcelona's main hospital at Vall d'Hebron.
Important city centre stations include Sants-Estació, Diagonal, Verdaguer, Sagrada Familia and Sagrera.
Lines L6, L7 and L8 are all run by Ferrocarrils de la Generalitat (FGC) and, although technically part of the metro system, use different trains, which are more comfortable than the regular metro trains.
* The Lilac L6 FGC-Metro Line goes from Plaça Catalunya to Reina Elisenda.
* The Brown L7 FGC-Metro Line goes from Plaça Catalunya to Avinguda Tibidabo.
* The Pink L8 FGC-Metro Line runs from Plaça Espanya to Molí Nou Ciutat Cooperativa.
Metro Line 9 is in two sections, the first of which opened in 2009 and runs from La Sagrera to Can Zam in Sant Coloma.
The second section opened in early 2016 and goes from Zona Universitària to Barcelona Airport.
The remaining section that runs through Barcelona City Centre is still under construction.
Metro Line 10 runs from La Sagrera to Gorg in Badalona.
This relatively new line also opened in 2009 and is planned to reach Zona Franca.
Metro Line 11 runs from Trinitat Nova to Can Cuiàs in Moncada i Reixach.
It serves a part of the city that was previously very difficult to reach by public transport and includes the stations Casa de l'Aigua, Torre Baró and Ciutat Meridiana.