near the grey river (Hase) Chasuarii. It may also be noted that Osnabrück is situated on the northern end of the Teutoburg Forest, which until the 19th century was known as the Osning. The way in which the city's name is pronounced can also serve as a means of telling if the speaker is a native of Osnabrück or a visitor: most locals stress the last syllable, while those from elsewhere tend to stress the first one. The city gave its name to the textile fabric of osnaburg. History Medieval Osnabrück initially developed as a marketplace next to the bishopric founded by Charlemagne, King of the Franks, in 780. Some time prior to 803, the city became the seat of the Prince-Bishopric of Osnabrück. Although the precise date is uncertain, it is likely that Osnabrück is the oldest bishopric in Lower Saxony. In the year 804 Charlemagne was said to have founded the Gymnasium Carolinum in Osnabrück. This would make it the oldest German Gymnasium school, but the charter date is disputed by historians, some of whom believe it could be a forgery. In 889 the town was given merchant, customs, and coinage privileges by King Arnulf of Carinthia. Osnabrück was first referred to in records as a "city" in 1147. A decade later, Emperor Frederick Barbarossa granted the city fortification privileges (Befestigungsrecht). Most of the towers which were part of the original fortifications are still visible in the city. Osnabrück became a member of the Hanseatic League in the 12th century, as well as a member of the Westphalian Federation of Cities. The history of the town in the later Middle Ages was recorded in a chronicle by Albert Suho, one of Osnabrück's most important clerics in the 15th century. Early Modern age From 1561 to 1639 there was a considerable amount of social unrest and tension in Osnabrück due to the Protestant Reformation, the Thirty Years' War and also witch hunting. In 1582, during the rule of Mayor Hammacher (1565–1588), 163 women were executed as alleged witches; most of them were burned alive. In total, 276 women were executed, along with 2 men who had been charged with wizardry. The first Lutheran services were held in Osnabrück in 1543. Over the next century, Lutheranism expanded in the city and several Protestant bishops were elected. However, the Catholic churches continued to operate, and the city never became completely Lutheran.