Oslo is the capital of and most populous city in Norway. Oslo constitutes a county and a municipality.
Founded around 1000 AD, and established a "kaupstad" or trading place in 1048 by King Harald III, the city was elevated to a bishopric in 1070 and a capital under Haakon V around 1300. Personal unions with Denmark from 1397 to 1523 and again from 1536 to 1814 and with Sweden from 1814 to 1905 reduced its influence. After being destroyed by a fire in 1624, the city was moved closer to Akershus Castle during the reign of King Christian IV and renamed Christiania in his honour. It was established as a municipality (formannskapsdistrikt) on 1 January 1838. Following a spelling reform, it was known as Kristiania from 1877 to 1925, when its original Norwegian name was restored.
Oslo is the economic and governmental centre of Norway. The city is also a hub of Norwegian trade, banking, industry and shipping. It is an important centre for maritime industries and maritime trade in Europe. The city is home to many companies within the maritime sector, some of which are among the world's largest shipping companies, shipbrokers and maritime insurance brokers. Oslo is a pilot city of the Council of Europe and the European Commission intercultural cities programme. Oslo is considered a global city and ranked "Beta World City" in studies performed by the Globalization and World Cities Study Group and Network in 2008. It was ranked number one in terms of quality of life among European large cities in the European Cities of the Future 2012 report by fDi Magazine. A survey conducted by ECA International in 2011 placed Oslo as the second most expensive city in the world for living expenses after Osaka. In 2013 Oslo tied with the Australian city of Melbourne as the fourth most expensive city in the world, according to the Economist Intelligence Unit (EIU)'s Worldwide Cost of Living study.
As of January 2014 the city of Oslo has a population of 634,000. The Metropolitan area of Oslo has a population of 1,502,604, of whom 951,581 live in the contiguous conurbation. The population currently increases at record rates, making it the fastest growing major city in Europe. This growth stems for the most part from immigration and high birth rates among immigrants, but also from intra-national migration. The immigrant population in the city is growing somewhat faster than the Norwegian population, and in the city proper is now more than 25%.