Vilnius ( VIL-nee-əs, Lithuanian: [ˈvʲɪlʲnʲʊs] ) is the capital of and largest city in Lithuania and the second-most-populous city in the Baltic states. The city's estimated July 2024 population was 605,270, and the Vilnius urban area (which extends beyond the city limits) has an estimated population of 708,627.

Vilnius is notable for the architecture of its Old Town, considered one of Europe's largest and best-preserved old towns. The city was declared a UNESCO World Heritage Site in 1994. The architectural style known as Vilnian Baroque is named after the city, which is farthest to the east among Baroque cities and the largest such city north of the Alps.

The city was noted for its multicultural population during the Polish–Lithuanian Commonwealth, with contemporary sources comparing it to Babylon. Before World War II and the Holocaust, Vilnius was one of Europe's most important Jewish centers. Its Jewish influence has led to its being called "the Jerusalem of Lithuania", and Napoleon called it "the Jerusalem of the North" when he passed through in 1812.

Vilnius was a 2009 European Capital of Culture with Linz in Austria. In 2021, the city was named one of fDi's 25 Global Cities of the Future. Vilnius is considered a global financial centre, ranked 76th globally and 29th in Europe on the Global Financial Centres Index. It hosted the 2023 NATO Summit. Vilnius is a member of Eurocities and the Union of Capitals of the European Union (UCEU).