Oldenburg (; Low German: Ollnborg; Saterland Frisian: Ooldenbuurich) is an independent city in the state of Lower Saxony, Germany. During the French annexation (1811–1813) in the wake of the Napoleonic war against Britain, it was also known as Le Vieux-Bourg in French. The city is situated at the Rivers Hunte and Haaren, in the northwestern region between the cities of Bremen in the east and Groningen (Netherlands) in the west. It has a population of 157,267 (May 2011). The formal name is Oldenburg (Oldenburg) or Oldenburg (Oldb) (spoken: Oldenburg in Oldenburg) to distinguish it from the city of Oldenburg in Holstein.
Archaeological finds point to a settlement dating back to the 8th century. The place was first mentioned in 1108 as Aldenburg in connection with Elimar I (also known as Egilmar I) who is now commonly seen as the first count of Oldenburg. The town gained importance due to its location at a ford of the navigable Hunte river. Oldenburg became the capital of the County of Oldenburg (later Duchy, Grand Duchy, and Free State), a small state in the shadow of the much more powerful Hanseatic city of Bremen.
In the 17th century, Oldenburg was a wealthy town in a time of war and turmoil and its population and power grew considerably. In 1667, the town was struck by a disastrous plague epidemic and, shortly after, a fire destroyed Oldenburg. The Danish kings, who were also counts of Oldenburg at the time, were not much interested in the condition of the town and it lost most of its former importance. In 1773, Danish rule ended. It was only then that the destroyed buildings in the city were rebuilt in a neoclassicist style. (In German, the ‘neoclassicist style’ of that period would usually be called klassizistisch, while neoklassizistisch specifically refers to the classicist style of the early 20th century.)
After German Emperor Wilhelm II was forced to abdicate following the exhaustion and defeat of the German Empire in World War I, monarchic rule ended in Oldenburg as well with the abdication of Grand Duke Frederick Augustus II of Oldenburg (Friedrich August II von Oldenburg) on 11 November 1918. The Grand Duchy of Oldenburg now became the Free State of Oldenburg (Freistaat Oldenburg), the city remained the capital.
In 1945, after World War II, the State of Oldenburg was part of the British zone of occupation. The British military government of the Oldenburg region resided in the city. Several displaced persons camps were set up in the city that had suffered only 1.4% destruction during the bombing campaigns of World War II. About 42,000 refugees migrated into Oldenburg, which raised the number of residents to over 100,000. In 1946, the Free State of Oldenburg was dissolved, and the area became the 'Administrative District' of Oldenburg (Verwaltungsbezirk Oldenburg) as part of the newly formed federal German state of Lower Saxony (Niedersachsen). The city was now capital of the district. In 1978, the district was dissolved and succeeded by the newly formed Weser-Ems administrative region (Regierungsbezirk Weser-Ems), again with the city as administrative capital. The State of Lower Saxony dissolved all regierungsbezirks by the end of 2004 in the course of administrative reforms.