Basel, Switzerland

Basel sits where Switzerland, France, and Germany meet along the Rhine, with roughly 180,000 residents. The Romanesque Münster Cathedral, consecrated in 1019, holds the tomb of the 16th-century humanist Erasmus. Within its 37 square kilometers, the city packs more than 40 museums, the highest density of any Swiss city. The Kunstmuseum, founded in 1661, ranks as the oldest public art museum in the world still open. Every June, the Art Basel fair, founded in 1970, draws the largest contemporary art crowds on the planet.