The history of the city can be traced back over 1,000 years. Oslo was founded in 1048, by the king Harald Hardråde. The city became capital of Norway around 1300, but lost its privileges during the Danish-Norwegian union from 1348 to 1814. In 1624, a fire devastated old Oslo, and the city was moved some kilometres west to gain protection from the fortress at Akershus. The city was renamed Christiania, after the Danish King Christian IV, a name that remained until it was officially renamed on January 1st 1925 to Oslo. Traces have been found close to Ekeberg indicating settlement as far back as 10,000 BC.
After the devastating 1624 fire, old Oslo (around the mouth of river Aker) was largely abandoned and the ruins converted to farmland. Today, a few church ruins are still visible under the Ekeberg hill (across the water from the new operahouse, between road E18 and the railway). Beyond these ruins there is virtually nothing remaining of medieval Oslo. Ironically, the new city Christiania was established outside the borders of Oslo, and 'Oslo' remained the name of the small, surviving settlement outside the new city borders. During Christiania's rapid expansion in the 19th century, as the capital of a new state, the site of the original Oslo (old Oslo, or 'Gamlebyen') was included in the city. Due to the rapid inclusion of surrounding agricultural areas in the 19th century, a large number of remains from the city's farming history is still clearly visible in place names and farm houses. The remains of historical pastures can be found at parks, St. Hanshaugen for example is now used as a recreational park for Oslo's residents.
Oslo, with its approximately 453 square kilometers, is one of the largest capitals in the world by area. Most of this is forest, making Oslo a city in close contact with the nature surrounding it.
Oslo is situated in an amphitheatre-like setting, with the city centre in the bottom close to the Oslofjord, and residential areas stretching uphill from there in all directions. Behind the residential areas, the forested area of Marka (Nordmarka, Østmarka, Lillomarka) extends, with flora and fauna that is quite extraordinary for a city of this size. Moose are commonplace (easily spotted in winter), and the whole of the capital is part of Norway's wolf reserve (a breeding couple is thought to have settled in Østmarka). However, polarbears are non-existing in Norway proper, even some might think so, due to old stories about Norway.
The Oslofjord is an inlet of the Skagerrak bay, stretching inland from the North Sea. In the reverse direction, the inlet runs towards Øresund and the Baltic Sea. Oslo has an impressive archipelago of islands, which in summer becomes the city's favoured playground.
The inner city centre is bounded by Oslo Central Station (Oslo S) to the east, the Royal Palace (Slottet) to the west and the seafront (from Akershus fortress to Aker brygge) to the south. It is fairly compact and easily walkable. Karl Johans gate, the mostly pedestrian main street connecting Oslo S and the Palace, is the main artery of downtown Oslo. However, several of the neighbourhoods close to the centre hold interesting sights and entertainment offerings, so to explore these you should make use of the city's comprehensive and modern public transport system.
Although well into the northern latitudes, Oslo's climate is fairly temperate thanks to warm air being wafted across the Atlantic from the Gulf Stream. Summer weather in Oslo is usually mild and pleasant, with frequent hot spells and plenty of long sunny days. In winter temperatures hover just above or below freezing, with occasional cold spells. Snow is most often plentiful in the forested areas, making Oslo a great winter sports venue. Rainfall is spread across the year, the rainiest month being August.
Oslo has a population of about 650,000 people, and nearly a million including its extra-municipal suburbs (such as Bærum and Lørenskog). It has the highest population growth of any European capital, with exorbitant real estate prices to match. The Oslo metropolitan area has a population of around 1.4 million. The diverse population includes some of Norway's wealthiest celebrities. About a quarter of the population are of non-Norwegian origin, the majority hailing from Sweden, Poland and Pakistan. This has made Oslo an ethnically and culturally diverse city. Accompanied by a large influx of people from all around Norway, Oslo is thus often referred to as the "melting pot" of Norway. Cultural differences have affected Oslo's society and cityscape in matters of cuisine and shopping, which have all blended in to the everyday life of Oslo's population. Some areas of Oslo, especially around Grønland and Tøyen, and some suburbs east of the city center have majority-immigrant or majority non-ethnic Norwegian populations. Oslo has for centuries been a remarkably segregated city, and there are still sharp differences between the different parts of the city, and attempts at decreasing this divide has been futile. There are notable immigrant communities of Pakistani, Somali, Swedish, Sri Lankan, Iraqi, Polish, Romanian, Vietnamese, Iranian, Ex-Yugoslavian, Moroccan, Turkish, Albanian, Filipino, Thai and Danish origin. Polish immigrants form the largest minority group in Oslo.
The Oslo region is the country's premier business center and has a diverse and dynamic economy with one of the highest regional GDPs in Europe. Figures published by the regional development agency for Oslo show that GDP per capita in the region was €44,190 ($51,950) (excluding oil and gas) in 2000, compared to an EU average of approximately €20,000 ($23,512). According to a report produced by the city's Chief Commissioner's Department and the Department of Finances and Development, the service sector dominates employment in Oslo. In 2001, Public and Business services accounted for more than 59 percent of jobs. Other major employment areas within the service sector include trade, hotels and catering, banking and insurance.
Following the latest reform of January 1, 2004, the city is divided into fifteen boroughs (bydeler) that are to a considerable extent self governed. Each borough is responsible for local services not overseen by the City Council, such as social services, basic healthcare, and kindergartens. For convenience, the city can be divided into six larger districts.