Usual tourist attractions often consist of picturesque natural attractions, museums, theme parks, and hip restaurants. But did you know that in Stockholm, Sweden, their subway system is an attraction in itself?

Experiencing one of the longest art galleries in the world is an adventure of a lifetime. Stockholm's subway system is more than just a means of transport for Swedish commuters. About 90 of its 100 stations are decorated intricately and with meaning that every station is bursting with its own story to tell.

The whole concept started during the 1950s when two local female artists fought for the idea of making breathtaking art in the Stockholm Subway System. They have won and now travelers and commuters can get a sneak peek into the history of Sweden through the means of art.

It's quite a trip to visit all the 90 stations. But if you're pressed for time, there are a couple of stations you must not miss on discovering. The art embedded in their walls tell of an important part in Sweden's history, and they are made to raise important questions about society. Here are some of them:

Universitetet. This station is found on the red line near Stockholm University and has opened in 1975. The original artwork on its walls was the work of Artist Pär Andersson, but it was almost completely destroyed 20 years later because of graffiti and dust. The walls were repainted back in 1997 by Belgian artist Françoise Schein and it promotes a deeper understanding of democracy and human rights.

Kungsträdgården. Ulrik Samuelson is the artist behind the beautiful artwork that adorns the walls of Kungsträdgården, an underground garden symbolizing life and nature. Samuelson also wants to depict the history of the former royal garden and the long-lost palace of Makalösa.

Solna Centrum. Bystanders might simply look at Solna Centrum's walls and be amazed by the intensity of colors, but it's really more than that. Artists Karl-Olov Björk and Anders Åberg created the art in hopes to let the public remember some problems Sweden had during the 1970s like rural depopulation, deforestation, and the environmental movement.

So the next time you visit Sweden, make sure to include making a trip to Stockholm's subway system in your itinerary. Until today, it's still considered one of the most beautiful metro stations in the world.