The Stockholm subway system today consists of 100 stations, of which about half are situated underground. The tunnel stretches are constructed partly in concrete, partly in rock, and make up 63.3 km of the system's total length of 110 km. This is one of the world's longest systems in terms of route length per inhabitant. The mechanical and technical designs used in Stockholm's subway are copied directly from the New York subway system, including the measurements of the rails themselves and the electrical power distribution system

The world´s longest art exhibition.
  At the end of the 1940's, when the first metro lines, Stockholm's underground railway system, were constructed, the idea was born that the stations might be decorated with works of art. These ideas were formulated into a proposition to the Stockholm City Council in 1955 which included the following words: "It may not be possible to make every station a fairy tale castle, but painters and sculptors, potters and artist craftsmen should be given the chance, together with architects and engineers, to make the metro stations generally attractive and stimulating environments, and make one or two main stations into underground cathedrals; a fanfare of colour, rhythm..." Every party supported the motion, which is why today you are able to experience exciting, beautiful and varying art in over 70 of the 100 stations. There are sculptures, mosaics and paintings. There are engravings and reliefs. In the tunnels you can see underground grottoes and verdant gardens, water pools, water lily pounds and fantastic mountain rooms. About 130 artists have helped to give Stockholm's metro colour, form and life. The works of art are constantly being cared for and developed and they have even awakened interest abroad. The Art Committee which is the body responsible for choosing the works of art, spends more than 2.5 million SEK every year on works of art in the metro. Take this pages as a guide and enjoy a journey through Stockholm´s 110 kilometre long art exhibition.