Lausanne ( loh-ZAN, US also loh-ZAHN; French: [lozan] ; Arpitan: Losena [lɔˈzəna] ) is the capital and largest city of the Swiss French-speaking canton of Vaud, in Switzerland. The Olympic capital, it is a hilly city situated on the shores of Lake Geneva, about halfway between the Jura Mountains and the Alps , and facing the French town of Évian-les-Bains across the lake. Lausanne is located (as the crow flies) 51.7 kilometres (32 miles) northeast of Geneva, the nearest major city. The Federal Supreme Court of Switzerland convenes in Lausanne, although it is not the de jure capital of the nation.

The municipality of Lausanne has a population of about 140,000, making it the fourth largest city in Switzerland after Basel , Geneva, and Zurich, with the entire agglomeration area having about 420,000 inhabitants (as of January 2019). The metropolitan area of Lausanne-Geneva (including Vevey-Montreux, Yverdon-les-Bains, Valais and foreign parts), commonly designated as Arc lémanique was over 1.3 million inhabitants in 2017 and is the fastest growing in Switzerland.