A humongous reserve about 7 km west of the city, Rotwildpark is a sprawling forest with a network of dirt paths and quiet paved roads. While almost all the park is runnable, the favorite section is around the sparkling waters of Barensee (Bear Lakes). The loop around the lakes is roughly 5 km, with plenty of options to double up or extend your route.
This park has numerous additional trails and paths, for either an easier run or a more involved trail run. We’ve not been able to find an online map, but there are resources once you get to the park.