This is a nice, green option about 2 miles south of Brussels Park. Using the paths of the two parks, it is possible to put together ~2.5 fairly hilly miles. The Parc de Forest is a graceful, grassy slant. Parc Duden is also hilly, with more rugged forest paths. For a longer run, enjoy the residential streets of the Forest neighborhood. To run to Parc de Forest from central Brussels, take Rue de Regence to the Palais de Justice, and then Rue de l’Hotel de Monnaies, which is ~2 miles.