Leipzig is a city in the federal state of Saxony, Germany. It has around 540,000 inhabitants and is the heart of the Central German Metropolitan Region. Leipzig is located about 150 kilometres south of Berlin at the confluence of the White Elster, Pleisse, and Parthe rivers at the southerly end of the North German Plain.Leipzig has been a trade city, since, at least the time of the Holy Roman Empire, sitting at the intersection of the Via Regia and Via Imperii, two important Medieval trade routes. At one time, Leipzig was one of the major European centers of learning and culture in fields such as music and publishing. After World War II, Leipzig became a major urban center within the German Democratic Republic, but its cultural and economic importance declined, despite East Germany being the richest economy in the Soviet Bloc.Leipzig later played a significant role in instigating the fall of communism in Eastern Europe, through events which took place in and around St. Nicholas Church. Since the reunification of Germany, Leipzig has undergone significant change with the restoration of some historical buildings, the demolition of others, and the development of a modern transport infrastructure. Leipzig today is an economic center in Germany and has a prominent opera house and one of the most modern zoos in Europe. Leipzig is nicknamed as the "Boomtown of eastern Germany" or "Hypezig".In December 2013, according to a study by Marktforschungsinstituts GfK, Leipzig was ranked as the most livable city in Germany and is one of the three European cities with the highest quality of living. In 2010, Leipzig was included in the top 10 cities to visit by the New York Times, and ranked 39th globally out of 289 cities for innovation in the 4th Innovation Cities Index published by Australian agency 2thinknow. Leipzig is currently listed as Gamma World City.