Zurich or Zürich is the largest city in Switzerland and the capital of the canton of Zurich. It is located in north-central Switzerland at the northwestern tip of Lake Zurich. The population of the town is about 400,028, the urban agglomeration 1.315 million and the Zurich metropolitan area 1.83 million. Zurich is a hub for rail, road and air traffic. Both Zurich Airport and the railway station are the largest and busiest in the country. Zurich has been permanently settled for about 2,000 years, founded by the Romans, who, in 15 BC, called it Turicum. However, settlements have been found as early as 6,400 years ago. During the Middle Ages, Zurich gained the independent and distinct status of an immediate empire, and in 1519, it became a major center of the Protestant Reformation in Europe under the leadership of Huldrych Zwingli. The official language of Zurich is German, but the main spoken language is the local variant of the German dialect of Zurich. Many museums and art galleries can be found in the city, including the Swiss National Museum and the Kunsthaus. Schauspielhaus Zurich is one of the most important theatres in the German-speaking world.