Turin is a city and an important business and cultural centre in northern Italy. It is the capital city of Piedmont and of the Metropolitan City of Turin, and was the first Italian capital from 1861 to 1865. The city is located mainly on the western bank of the Po River, in front of Susa Valley, and is surrounded by the western Alpine arch and Superga Hill. The population of the city proper is 875,698 (31 December 2018) while the population of the urban area is estimated by Eurostat to be 1.7 million inhabitants. The Turin metropolitan area is estimated by the OECD to have a population of 2.2 million.