The Madrid Metro is the sixth longest underground passenger transport in the world, although the city of Madrid, is just the 60th, in the ranking of population. The growth of Metro de Madrid in the last 20 years, has been very rapid.
The first line of the Madrid Metro started operating on the 17th, October 1919, with 8 stations, and 3.5 Kms. (2.2 Miles).
The extension of this line, and the construction of two more followed soon after. In 1936, the network had three lines and a branch line, which still exists today, between the Opera Square, and the North Train Station, today called, Príncipe Pío.
All these stations served as air raid shelters during the Spanish Civil War.
In the early seventies, the network expanded significantly to take account of the population growth, urban expansion, and economic boom in Madrid.
In the late 70s, there was a crisis of mismanagement, and after that, on the 80s, the works were resumed, reaching 100 Kms. (62 Miles) of railroad tracks.
In the early nineties, Metro de Madrid was formed as the public company to unite all the management. This carried out, large expansion projects, like the extension of lines 1, 4 and 7, and the construction of new lines 8 and 11, to reach the outskirts of Madrid. Line 8 was built to extend the metro network, all the way to Barajas Airport.
The lengthening of line 9, made it to be the first line to give service to the outskirts of Madrid. This Metro Line, went all the way to Rivas-Vaciamadrid, and Arganda del Rey. These are two towns located to the southeast of Madrid.
In the decade 2000, there was a huge project of almost 50 km (31 miles) of tunnels for the new Metro. This construction included a direct connection between downtown Madrid (Nuevos Ministerios), and Barajas Airport.
Also, in this same decade, another large addition was made to the service, with a big loop of 40 km, called Metrosur. This provided the service to the southern suburbs of Madrid.
MetroSur, is one of the largest civil engineering projects in Europe. It was inaugurated on April 11, 2003. This includes 41 kms. (25 miles) of tunnels and 28 new stations, which connect to Madrid city center. This loop also connects the five suburb towns, located south of Madrid, which are: Getafe, Móstoles, Alcorcón, Fuenlabrada and Leganes.