The national forest covers 1,150ha on a rugged plateau between Sèvres and Villacoublay. Take the Route des Bois-Blancs to the Étoile du Pavé de Meudon, a nearby promontory with a view over the Viroflay woods. From there, along the Route des Treize Ponts, head to the Chêne des missions, a megalithic site recreated in 1895. The forest road skirts the ponds of Chalais and Trivaux, winding through woodland. Over 16.5km of paths await hikers!