Oslo is the capital and the most populous city in Norway. 

Founded in the year 1040, and established as 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 Fortress 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, at which time 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.

Oslo is considered a global city and ranked "Beta World City" in studies carried out 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 Tokyo.

As of January 1, 2016, the municipality of Oslo has a population of 658,390, while the population of the city's urban area was 942,084. The metropolitan area had an estimated population of 1.71 million. The population is currently increasing at record rates, making it the fastest growing major city in Europe.

Source: Wikipedia