"Last but certainly not least is Stockholm. Sweden's capital city is made of 14 islands connected by a robust public transport network including a metro system with 100 stations, ferries, buses, and trams. Stockholm’s metro, the Tunnelbana (or T-bana) forms the world’s longest art gallery. Though initially envisioned as a way to reduce traffic, Stockholm’s underground embraces another worthy goal: making art accessible to people of all economic backgrounds. Today, 94 of the T-bana’s 100 stations feature the work of 250 artists, including paintings, sculptures, and large-scale installations. The art at most stations depicts the history and culture of the surrounding neighborhoods, providing a colorful escape from the city’s gray winters. If you have a chance to visit, don’t miss the otherworldly Rådhuset station or Solna Centrum. The red cave-like ceiling mimics a forest sunset—look closer and you’ll find sporadic wall illustrations depicting social commentary from 1970s Sweden. Free guided art tours are available from June to August every Tuesday, Thursday, and Saturday at 3p.m., starting from the SL Customer Centre at T-Centralen. As you’d expect, the Stockholm metro is clean, climate-controlled, and sustainable. When you’re done soaking in the stunning stations of Stockholm metro, you can also see the city and attractions by ferry, for the same price as a bus or metro ticket (SEK 42 or about $3.86). How to experience it: To see Stockholm from the water, hop on the SL ferry line 80 and visit popular tourist attractions such as the Abba museum or wander around nature in Djurgården, a National City Park."
