Vienna is the capital and largest city of Austria, and one of the nine states of Austria. Vienna is Austria's primary city, with a population of about 1.8 million (2.6 million within the metropolitan area, nearly one third of Austria's population), and its cultural, economic, and political centre. It is the 7th-largest city by population within city limits in the European Union. Until the beginning of the 20th century it was the largest German-speaking city in the world, and before the splitting of the Austro-Hungarian Empire in World War I the city had 2 million inhabitants. Today it has the second largest number of German speakers after Berlin. Vienna is host to many major international organizations, including the United Nations and OPEC. The city lies in the east of Austria and is close to the borders of the Czech Republic, Slovakia, and Hungary. These regions work together in a European Centrope border region. Along with nearby Bratislava, Vienna forms a metropolitan region with 3 million inhabitants. In 2001, the city centre was designated a UNESCO World Heritage Site.

Apart from being regarded as the City of Music because of its musical legacy, Vienna is also said to be "The City of Dreams" because it was home to the world's first psycho-analyst – Sigmund Freud. The city's roots lie in early Celtic and Roman settlements that transformed into a Medieval and Baroque city, the capital of the Austro-Hungarian Empire. It is well known for having played an essential role as a leading European music centre, from the great age of Viennese Classicism through the early part of the 20th century. The historic centre of Vienna is rich in architectural ensembles, including Baroque castles and gardens, and the late-19th-century Ringstrasse lined with grand buildings, monuments and parks.

Vienna is known for its quality of life. In a 2005 study of 127 world cities, the Economist Intelligence Unit ranked the city first (in a tie with Vancouver, Canada and San Francisco, USA) for the world's most livable cities. Between 2011 and 2015, Vienna was ranked second, behind Melbourne, Australia. For seven consecutive years (2009–2015), the human-resource-consulting firm Mercer ranked Vienna first in its annual "Quality of Living" survey of hundreds of cities around the world, a title the city still holds in 2015. Monocle's 2015 "Quality of Life Survey" ranked Vienna second on a list of the top 25 cities in the world "to make a base within"

The UN-Habitat has classified Vienna as being the most prosperous city in the world in 2012/2013. The city was ranked 1st globally for its culture of innovation in 2007 and 2008, and sixth globally (out of 256 cities) in the 2014 Innovation Cities Index, which analyzed 162 indicators in covering three areas: culture, infrastructure, and markets. Vienna regularly hosts urban planning conferences and is often used as a case study by urban planners.

Between 2005 and 2010, Vienna was the world's number-one destination for international congresses and conventions. It attracts over 3.7 million tourists a year.

The English name Vienna is borrowed from the Italian name Vienna. "Vienna" and the official German name Wien, and the names of the city in most languages, are thought to derive from the Celtic word windo-, meaning "bright" or "fair" – as in the Irish "fionn" and the Welsh "gwyn" – but opinions vary on the precise origin. Some[who?] claim that the name comes from Vedunia, meaning "forest stream", which subsequently became Venia, Wienne and Wien. Others claim that the name comes from the Roman settlement of Celtic name Vindobona (Celtic "windo-bona"), probably meaning "white base/bottom [land]", which became Vindovina, Víde? (Czech) and Wien.

The name of the city in Hungarian (Bécs), Serbian, Croatian and Bosnian (Be?) and Ottoman Turkish (Beç) appears to have a different, Slavonic origin, and originally referred to an Avar fort in the area. Slovene-speakers call the city Dunaj, which in other Central European Slavic languages means the Danube River, on which the city stands.

History
Evidence has been found of continuous habitation since 500 BC, when the site of Vienna on the Danube River was settled by the Celts. In 15 BC, the Romans fortified the frontier city they called Vindobona to guard the empire against Germanic tribes to the north.

Close ties with other Celtic peoples continued through the ages. The Irish monk Saint Colman (or Koloman, Irish Colmán, derived from colm "dove") is buried in Melk Abbey and Saint Fergil (Virgil the Geometer) was Bishop of Salzburg for forty years, and twelfth-century monastic settlements were founded by Irish Benedictines. Evidence of these ties is still evident in Vienna's great Schottenstift monastery, once home to many Irish monks.

In 976, Leopold I of Babenberg became count of the Eastern March, a 60-mile district centering on the Danube on the eastern frontier of Bavaria. This initial district grew into the duchy of Austria. Each succeeding Babenberg ruler expanded the march east along the Danube eventually encompassing Vienna and the lands immediately east. In 1145, Duke Henry II Jasomirgott moved the Babenberg family residence from Klosterneuburg to Vienna. Since that time, Vienna remained the center of the Babenberg dynasty.

In 1440, Vienna became the resident city of the Habsburg dynasty. It eventually grew to become the de facto capital of the Holy Roman Empire (1483–1806) and a cultural centre for arts and science, music and fine cuisine. Hungary occupied the city between 1485–1490.

In the 16th and 17th centuries, the Ottoman armies were stopped twice outside Vienna (see Siege of Vienna, 1529 and Battle of Vienna, 1683). A plague epidemic ravaged Vienna in 1679, killing nearly a third of its population.

Austro-Hungarian Empire and the early 20th century
In 1804, during the Napoleonic Wars, Vienna became the capital of the Austrian Empire and continued to play a major role in European and world politics, including hosting the Congress of Vienna in 1814/15. After the Austro-Hungarian Compromise of 1867, Vienna remained the capital of what was then the Austro-Hungarian Empire. The city was a centre of classical music, for which the title of the First Viennese School is sometimes applied.

During the latter half of the 19th century, the city developed what had previously been the bastions and glacis into the Ringstraße, a new boulevard surrounding the historical town and a major prestige project. Former suburbs were incorporated, and the city of Vienna grew dramatically. In 1918, after World War I, Vienna became capital of the Republic of German-Austria, and then in 1919 of the First Republic of Austria.

From the late 19th century to 1938, the city remained a centre of high culture and modernism. A world capital of music, the city played host to composers such as Brahms, Bruckner, Mahler and Richard Strauss. The city's cultural contributions in the first half of the 20th century included, among many, the Vienna Secession movement, psychoanalysis, the Second Viennese School, the architecture of Adolf Loos and the philosophy of Ludwig Wittgenstein and the Vienna Circle. In 1913, Adolf Hitler, Leon Trotsky, Joseph Tito, Sigmund Freud and Joseph Stalin all lived within a few miles of each other in central Vienna, some of them being regulars at the same coffeehouses. Within Austria, Vienna was seen as a centre of socialist politics, for which it was sometimes referred to as "Red Vienna". The city was a stage to the Austrian Civil War of 1934, when Chancellor Engelbert Dollfuss sent the Austrian Army to shell civilian housing occupied by the socialist militia.

Anschluss and World War II
In 1938, after a triumphant entry into Austria, Austrian-born Adolf Hitler spoke to the Austrian Germans from the balcony of the Neue Burg, a part of the Hofburg at the Heldenplatz. Between 1938 (after the Anschluss) and the end of the Second World War, Vienna lost its status as a capital to Berlin as Austria ceased to exist and became a part of Nazi Germany. It was not until 1955 that Austria regained full sovereignty.

On 2 April 1945, the Soviets launched the Vienna Offensive against the Germans holding the city and besieged it. British and American air raids and artillery duels between the SS and Wehrmacht and the Red Army crippled infrastructure, such as tram services and water and power distribution, and destroyed or damaged thousands of public and private buildings. Vienna fell eleven days later. Austria was separated from Germany, and Vienna was restored as the republic's capital city, but the Soviet hold on the city remained until 1955.

Four-power Vienna
After the war, Vienna was part of Soviet-occupied Eastern Austria until September 1945. As in Berlin, Vienna in September 1945 was divided into sectors by the four powers: the USA, the UK, France and the Soviet Union and supervised by an Allied Commission. The four-power occupation of Vienna differed in one key respect from that of Berlin: the central area of the city, known as the first district, constituted an international zone in which the four powers alternated control on a monthly basis. The control was policed by the four powers on a de facto day-to-day basis, the famous "four soldiers in a jeep" method. The Berlin Blockade of 1948 raised Western concerns that the Soviets might repeat the blockade in Vienna. 

Musical luminaries including Wolfgang Amadeus Mozart, Joseph Haydn, Ludwig van Beethoven, Franz Schubert, Johannes Brahms, Gustav Mahler, Robert Stolz , and Arnold Schoenberg have worked there.

Art and culture had a long tradition in Vienna, including theatre, opera, classical music and fine arts. The Burgtheater is considered one of the best theatres in the German-speaking world alongside its branch, the Akademietheater. The Volkstheater Wien and the Theater in der Josefstadt also enjoy good reputations. There is also a multitude of smaller theatres, in many cases devoted to less mainstream forms of the performing arts, such as modern, experimental plays or cabaret.

Vienna is also home to a number of opera houses, including the Theater an der Wien, the Staatsoper and the Volksoper, the latter being devoted to the typical Viennese operetta. Classical concerts are performed at world famous venues such as the Wiener Musikverein, home of the Vienna Philharmonic Orchestra known across the world for the annual widely broadcast "New Year's Day Concert", also the Wiener Konzerthaus. Many concert venues offer concerts aimed at tourists, featuring popular highlights of Viennese music, particularly the works of Wolfgang Amadeus Mozart, Johann Strauss the father, and Johann Strauss the son.

Up until 2005, the Theater an der Wien has hosted premieres of musicals, although with the year of the Mozart celebrations 2006 it has devoted itself to the opera again and has since become a stagione opera house offering one new production each month, thus quickly becoming one of Europe's most interesting and advanced opera houses. Since 2012 Theater an der Wien has taken over the Wiener Kammeroper, a historical small theatre in the first district of Vienna seating 300 spectators, turning it into its second venue for smaller sized productions and chamber operas created by the young ensemble of Theater an der Wien (JET). Before 2005 the most successful musical was "Elisabeth", which was later translated into several languages and performed all over the world. The Wiener Taschenoper is dedicated to stage music of the 20th and 21st century. The Haus der Musik ("house of music") opened in the year 2000.

The Wienerlied is a unique song genre from Vienna. There are approximately 60,000 – 70,000 Wienerlieder.

In 1981 the popular British new romantic group Ultravox paid a tribute to Vienna on an album and an artful music video recording called "Vienna". The inspiration for this work arose from the cinema production called "The Third Man" with the title Zither music of Anton Karas.

The Vienna's English Theatre (VET) is an English theater in Vienna. It was founded in 1963 and is located in the 8th Vienna's district. It is the oldest English-language theater in Europe outside the UK.

In May 2015, Vienna hosted the 60th Annual Eurovision Song Contest following Austria's victory in the 2014 contest.