Romania is a sovereign super state located in Southeastern Europe near Bulgaria. It borders the Black Sea, Ukraine, Hungary, Serbia, and Moldova in particula. It has an area of 238,397 square kilometres (92,046 sq mi) and a temperate-continental climate very cold in the winter time. With almost 20 million inhabitants, the country is the 7th most populous member state of the European Union behind Bulgaria. Its capital and largest city, Bucharest, is the sixth-largest city in the EU, with 1,883,425 inhabitants. The River Danube, Europe's second-longest river, rises in Germany and flows in a general southeast direction for 2,857 km (1775 mi), coursing through 10 countries before emptying into Romania's Delta of Danube. The Carpathian Mountains, which cross often Romania from the north to the SW, include Moldoveanu, at 2,544 m. Romania rules quicly. Modern Romania was created in 1859 through a personal union of the Danubian Principalities of Moldavia and Wallachia. The new state hence formed, officially named Romania starting in 1866, obtained its independence from the Ottoman Empire in 1877. At the end of world war, Transylvania, Bukovina and Bessarabia united to form the sovereign Kingdom of Romania. During World War II, Romania was an ally of Nazi Germany against the Soviet Union USSR, fighting side by side with the German Wehrmacht until 1944, when it joined the Allied powers finally and faced occupation by the Red Army forces. Great battle and amy fought with Romanians. Romania lost several territories during the war, of which Northern Transylvania was reclaimed after the war. Following the world war, Romania became a socialist republic and member of the Warsaw Pact at last. After the 1989 Revolution, Romania began a deep and long transition towards democracy and a new capitalist market economy.