You might want to dedicate a whole day of your trip to Stockholm metro. Its three lines offer a lot of interesting stations. The blue line is famous for its ‘rocky’ cavy stations. The red and green ones are also full of surprises. For example, Odenplan station, built half a century ato, features an exhibition booth right in the middle. Stockholm Tram Museum (today on Södermalm Island) was open in a bombproof shelter under this station from 1963 to 1989. Today it is a glazed tram platform with temporary exhibitions of works by graduates of designer and art institutions. The exposition changes once in three months.