As Austria's capital, Vienna is also the country's biggest city and one of its nine states. Located at the heart of the country's cultural, economic, and political spheres, Vienna is Austria's most populous city with almost two million residents (2.9 million in the metropolitan region). It is the biggest city on the Danube River and the EU's sixth most populous city proper.
Before the Austro-Hungarian Empire divided during World War I, Vienna had two million residents, making it the biggest German-speaking metropolis in the world. After Berlin, it is now the biggest German-speaking city in the country. The United Nations, OPEC, and the Organization for Security and Co-operation in Europe (OSCE) are all headquartered in Vienna. The city is nestled in Austria's easternmost region, just over the border from the Czech, Slovak, and Hungarian Republics. There is a European Centrope border area where all of these places function together. Vienna is part of a three-million-person metropolis that includes Bratislava, which lies only over the border. It was included on the World Heritage in Danger list in July 2017. Vienna is also known as the "City of Music" because of its rich musical history, which includes the likes of Beethoven and Mozart. Sigmund Freud, the world's first psychologist, was born and raised in Vienna, making it the "City of Dreams." Early Celtic and Roman villages were the ancestors of Vienna, which evolved into a Medieval and Baroque metropolis. From the time of Viennese Classicism until the beginning of the twentieth century, it was a major European music centre. While the late-19th-century Ringstraße is flanked with majestic buildings, monuments, and parks that ring Vienna's historic centre, there are many more architectural ensembles to be seen.
The excellent standard of living in Vienna is well-known. Economist Intelligence Unit recognised Vancouver and San Francisco as the world's most livable cities in a survey of 127 cities conducted in 2005. Vienna was the runner-up from 2011 through 2015, just ahead of Melbourne. Monocle's 2015 "Quality of Life Survey" placed Vienna as the second best city "to create a base inside" in the globe. Monocle's 2012 "Quality of Life Survey" placed Vienna at number four on a global ranking of best 25 cities to "build a base inside" (up from sixth in 2011 and eighth in 2010). In 2012–2013, UN-Habitat ranked Vienna as the world's most wealthy city. According to the 2014 Innovation Cities Index, which looked at 162 variables across three distinct domains—culture, infrastructure, and markets—the city was first in the world in 2007 and 2008 for its innovation culture and sixth in the world (out of 256 cities) in 2014. Urban planners often utilise Vienna as a case study because of its frequent hosting of urban planning conferences. The most popular city in the world for international conventions and conferences from 2005 to 2010. More than 6.8 million people visit each year.