Osnabruck is a city in Lower Saxony, Germany, some 80 km NNE of Dortmund, 45 km NE of Munster, and some 100 km due west of Hanover. It lies in a valley penned between the Wiehen Hills and the northern tip of the Teutoburg Forest. Osnabruck developed as a marketplace next to the bishop's see founded by Charlemagne, king of the Franks, 780. Some time before 803, the city became seat of the Prince-Bishopric of Osnabruck. Although the precise date is uncertain, Osnabruck is likely the oldest bishopric in Lower Saxony.