From Saint-Cyr-l'École to Villiers-Saint-Frédéric through the Yvelines

Access: Saint-Cyrstation on the RER C or Transilien N or U.

The trail is marked along its entire length with the red and white GR® markings.

(S) From Saint-Cyr station, go under the tracks and turn left onto the steep Rue Francisco Ferrer, which climbs up to the plateau. Continue along the straight road that runs alongside Camp de Satory. Continue until you reach the car park at the end of the road in the Versailles forest, where you will find the GR® coming from the left, near the N12.

(1) Continue straight ahead into Bois Robert, staying on the same side of the main road. Then turn right twice in the woods to reach Rue de Bièvres in the residential neighbourhoods of Saint-Cyr. Immediately turn left onto Impasse de Bièvres. Reach Chemin des Avenues and turn right onto it until you reach the roundabout.

(2) Turn left onto Boulevard Henri Barbusse, cross the railway tracks, then take the stairs a little further on the right. Continue straight ahead on Rue du Pont de Dreux, which bends to the right, then turn left onto Avenue Pierre Curie. Cross a bridge over a railway line and immediately turn right onto Chemin du Terrier Blanc.

(3) Continue along Chemin du Terrier Blanc to enter Bois Cassé. Continue straight ahead to the small hill, which you can climb to enjoy a panoramic view to the north with an orientation table, provided the trees are not too dense.

(4) Continue through the woods in the same direction until you reach the A12 motorway. Follow it to the right along a small path that descends quite steeply (caution: tricky passage!) and climb up opposite to cross the motorway above a tunnel, following the railway line.

(5) Continue through the woods along the railway line, initially until you reach the entrance to Fontenay-le-Fleury station.

(6) Continue straight ahead to the D127 and cross it (caution: fairly busy road).

(7) After crossing, follow the road through the woods, then turn left along the railway embankment, keeping to the left of the old fortified batteries, one of which houses the National Archives of the National Centre for Cinematography. Continue along the railway line for a good kilometre (beware of possible muddy conditions in wet weather), then head back into the woods following the path until you reach a wider track on the right.

(8) Take this path, then take the second straight path on the right down the embankment before going back up at the next crossroads. Then take the leftmost path that climbs back up to the plateau and continue straight ahead to the picnic area in front of the equestrian centre at the entrance to Bois-d'Arcy (you can shorten the descent and climb back up the embankment by continuing straight ahead on the plateau path. You will then rejoin the GR® on the^second path on the left).

(9) Take the Route Forestière des Clayes on the right, which is wider and more comfortable than the steep paths taken previously. Follow it straight ahead for more than 2 km.

(10) Pass the entrance to Clayes-sous-Bois. Follow the road as it veers to the left and continue straight ahead until you reach a crossroads where two paths branch off to the right, before the end of the forest road.

(11) Take the second path on the right to descend towards the centre of Plaisir via the Chemin de la Butte de la Cranne. Turn left onto Rue de la Brétéchelle.

(12) Continue straight ahead, pass under the D30, then reach the church and castle via Rue Émile Zola on the left after the castle park wall.

(13) From the church square, don't hesitate to enter the castle grounds if they are open to visitors, provided you exit by the same route (there is no guarantee that there will be an accessible exit on the other side of the grounds...). Continue opposite the church on Rue de la République, then take Rue Pasteur on the left in front of the town hall, then turn sharply left after the shopping centre. Continue straight on Rue du Bois, then take the fourth street on the right, Rue Ernest Lavisse. Then turn left onto Rue Edmond Rostand and reach the edge of the woods after an uphill climb, before reaching the high-voltage power lines.

(14) Turn right, pass under the power lines and descend into the next valley, then immediately climb back up on the opposite side. Once at the top, turn left. Continue along the Route Forestière, which crosses the entire wood, until you reach the picnic area.

(15) Take the track on the right towards Neauphle-le-Château. Join the D134, follow it for about 100 metres at the entrance to the village, then turn left into the woods.

(16) Go down Chemin Pierreux towards Jouars-Pontchartrain. Turn right onto Chemin de Bricassard, then right again onto Rue de Neauphle. Continue until you reach a path between the houses on the right after Rue de la Gouttière. Follow this path to rejoin Rue de la Gouttière a little further on. Follow it to the foot of the stairs.

(17) Climb the stairs to reach the centre of Neauphle, located on a promontory. When you reach Grande Rue, turn right, then left onto Place du Marché, until you reach the church just behind it.

(18) Go around the church on your right, then away from it. Continue left on Rue Saint-Jean, then start down the stairs that extend from it.

(19) Cross the road and continue down the path opposite. Cross the woods to arrive near a school in Villiers-Saint-Frédéric.

(20) Turn right onto Sentier des Écoles to reach Rue Charles de Gaulle.

(21) You can take a detour by turning right to the church located in Cour de la Ferme behind a stone porch.

(22) Return to Rue Charles de Gaulle.

(21) Continue straight ahead. Take the Sac à Vin path, the second on the right.

(23) Continue straight ahead after the Sac à Vin path until you reach the bridge under the railway line. Turn left just after the bridge to reach Villiers-Neauphle-Pontchartrain station.

This is where the radial section of the GR® 11 coming from Neauphle-le-Château and Paris meets the circular section that arrives perpendicularly to the left and right. In the itinerary described here, the circular section will be described in a clockwise direction, so starting to the right from here in the next stage.

(24) After turning left, follow the GR® between the railway line and the business park. Turn right at the level crossing and join the D191.

(25) The GR® crosses the D191, but to finish the stage, turn left and follow the road to Villiers-Neauphle-Pontchartrain station, located a little further on the left (E).

Arrival: Villiers-Neauphle-Pontchartrain station, on the Transilien N line, Paris-Dreux branch.

(S) Departure from Saint-Cyr station. Many trains on lines C, N and U serve this station (3 to 5 trains per hour in each direction).

(E) Arrival at Villiers-Neauphle-Pontchartrain station on the Paris-Dreux branch of line N (Montparnasse network). One train per hour in each direction.

The GR® follows the N line more or less closely throughout this stage. It is therefore possible to complete this stage in several stages by stopping at one of the intermediate stations. The halfway point is at Les Clayes-sous-Bois, close to three easily accessible stations (Villepreux-les-Clayes, Plaisir-les Clayes and Plaisir-Grignon).

There are a few tricky sections to mention, as some paths can be steep and muddy in wet weather, particularly in the Fontenay-le-Fleury and Bois d'Arcy areas. Good footwear is essential!

Hike completed on 3 March 2024 with the aim of covering the entire GR® 11.

• Fortified batteries in the Missionnaires forest in Bois d'Arcy (7)
• Saint-Pierre Church and Plaisir Castle (13)
• Centre of Neauphle-le-Château (and its Saint-Nicolas Church) on a promontory (18)
• Saint-Frédéric Church in Villiers-Saint-Frédéric (22)