Osnabrück is a city in Lower Saxony in western Germany. It is situated on the river Hase in a valley penned between the Wiehen Hills and the n…Osnabrück is a city in Lower Saxony in western Germany. It is situated on the river Hase in a valley penned between the Wiehen Hills and the northern tip of the Teutoburg Forest. With a population of 168,145 Osnabrück is the fourth largest city in Lower Saxony.