This is a great option near the city for those looking to do some hills and easy to moderate trail running. Just west of the city is the Stadtwald (Town Forest), comprised of Grafenberger Wald, and Aaper Wald. It’s possible to put together an 8+ km (5.2 mile) loop combining the four main trails: A1 to A4. See the route map and description posted by our friend Keith Hauser.
Another good option is a 6.8 km (4.3 mile) jogging trail, located in the Aaper Wald — on their trail map kiosk.