RER B "Saint-Rémy-lès-Chevreuse" station, or park in the Espace Jean Racine car park.
(S/E) The hike begins in front of the RER B station in Saint-Rémy-lès-Chevreuse. Head left to the roundabout to join the cycle path, then follow it towards Chevreuse. Take in the vast meadow where you can see the Domaine de Coubertin in the distance. Continue to the Coubertin farm.
(1) Take the path on the left and walk alongside the farm.
(2) At the entrance to the woods, go through the gate and continue uphill along a sunken path until you reach the plateau.
(3) When you reach the plateau, take the large path on the right and continue to the junction of plots 19 and 15.
(4) Turn left, pass the picnic tables, cross the road and walk along the edge of the woods to reach Meridon Castle. Cross the car park on the right.
(5) Enter the Meridon Departmental Forest and walk for about 300 metres until you reach plot 29.
(6) Between plots 28 and 29, turn right towards La Forge, cross a road and then, a little further on, cross the Ecosse Bouton stream at La Braquerie to reach the D906.
(7) Cross the road carefully and continue opposite , at the edge of the woods. 300 metres further on, you will see Mauvières Castle on your right. Continue straight ahead, then pass under the Yvette bridge, with Étang du Pré Joly on your left, and you will reach the D58, Route de Dampierre.
(8) Follow the road to the right, pass a few houses, then continue along the road for another 200 metres.
(9) Turn left onto the path that climbs Côte de Mauvières in the Bois de Mauvières, take the hairpin bend to the right, and you will come to a road, Ruelle aux Bœufs
(10) Turn right, cross the hamlet of Jagny, then enter the woods and continue for about 1 km.
(11) Before the Chevreuse cemetery, turn left onto a small path, then right onto Rue du 8 Mai 1945. Turn left onto Rue Jean Mermoz, and pass in front of the Philippe Dugué Hospital and the Hepad du Centre de Gérontologie.
(12) Cross the river and continue straight ahead, leaving the Irène Joliot Curie nursery school on your right. Turn right onto Rue de Versailles, then left onto Sentier des Remparts. Further on, this road becomes a small path that winds its way to the Château de la Madeleine (follow the signs carefully).
(13) Descend the winding path towards the south. A little further on, go down the stairs and you will come to a road. Follow it for about 50 metres, then continue down the stairs on the left until you reach Rue de Paris.
(14) Continue straight ahead, cross Place des Halles, and pass in front of the Tourist Office.
(15) At the Grataloup Museum, turn left onto Passage du Prieuré, then right onto Rue de la Division Leclerc, and immediately left onto Rue des Mandars. You will arrive at the Yvette River. Cross the river.
(16) On the other side, follow it to the left along the promenade, cross a road and continue straight ahead, cross another road and go straight ahead. Cross Rue de l'Yvette and continue to follow the river on the other bank.
(17) Turn right onto Rue des Ponts Blonniers and continue to the Coubertin farm.
(1) Turn left, following the cycle path, to return to Saint-Rémy-les Chevreuse station via the same route you took on the way there. (S/E)

(Coubertin farm, chestnut picking, ice cream parlour, for example).