The city's rapid population growth in the late 20th century was primarily a result of Norway's booming offshore oil industry. Today the oil industry is a key industry in the Stavanger region and the city is widely referred to as the Oil Capital of Norway.[not in citation given] The largest company in the Nordic region, Norwegian energy company Statoil is headquartered in Stavanger. Multiple educational institutions for higher education are located in Stavanger. The largest of these is the University of Stavanger.
Domestic and international military installations are located in Stavanger, among these is the North Atlantic Treaty Organisation's Joint Warfare Center. Other international establishments, and especially local branches of foreign oil and gas companies, contribute further to a significant foreign population in the city. Immigrants make up 11.3% of Stavanger's population. Stavanger has since the early 2000s consistently had an unemployment rate significantly lower than the Norwegian and European average. In 2011, the unemployment rate was less than 2%. The city is also among those that frequent various lists of expensive cities in the world, and Stavanger has even been ranked as the world's most expensive city by certain indexes.
Stavanger is served by international airport Stavanger Airport, Sola, which offers flights to cities in most major European countries, as well as a limited number of intercontinental charter flights. The airport was named most punctual European regional airport by flightstats.com in 2010.
Every two years, Stavanger organizes the Offshore Northern Seas (ONS), which is the second largest exhibition and conference for the energy sector. Gladmat food festival is also held each year and is considered to be one of Scandinavia's leading food festivals. The city is also known for being one of the nation's premier culinary clusters. Stavanger 2008 European Capital of Culture. Stavanger was awarded the 2008 European Capital of Culture alongside Liverpool.
The first traces of settlement in the Stavanger region come from the days when the ice retreated after the last ice age c. 10,000 years ago. A number of historians have argued convincingly that North-Jæren was an economic and military centre as far back as the 9th and 10th centuries with the consolidation of the nation at the Battle of Hafrsfjord around 872. Stavanger grew into a center of church administration and an important south-west coast market town around 1100–1300.
Stavanger fulfilled an urban role prior to its status as city (1125), from around the time the Stavanger bishopric was established in the 1120s. Bishop Reinald, who may have come from Winchester, England, is said to have started construction of Stavanger Cathedral (Stavanger domkirke) around 1100. It was finished around 1125, and the city of Stavanger counts 1125 as its year of foundation.
With the Protestant Reformation in 1536, Stavanger's role as a religious center declined, and the establishment of Kristiansand in the early 17th century led to the relocation of the bishopric. However, rich herring fisheries in the 19th century gave the city new life.