A circular loop around the Forest of Rosny

Departure from Rosny-sur-Seine station (Transilien line J, on the section between Paris-Saint-Lazare and Vernon; car park).

(S/E) Head west and follow Rue de la Gare. At the roundabout, turn right, go under the railway bridge and immediately turn left into Rue du Midi. Continue straight on, parallel to the railway line, then after a right-hand bend, you will come out onto Rue Sully and follow it to the left.

(1) At the end of the street, turn left and pass under the railway line again. Turn right into Rue des Gâts, then turn right into Chemin de la Villeneuve. Follow a stream and continue along the main path marked in yellow.

(2) At the junction, follow a path to the right which climbs and crosses a clearing (viewpoint). Descend through the woodland, come out onto a small road and follow it for a few dozen metres to the right. Then turn left onto a path through the woodland (yellow markings). The climb leads to a viewpoint featuring a decorated gazebo (distant view of the Seine cliffs and, in the distance, Vétheuil and La Roche-Guyon).

(3) Continue along the path marked in yellow, then take a left-hand bend. Further on, you’ll come out onto a small road; follow it to the left. Pass the Châtillon Forest House and reach a junction.

(4) Then turn right, pass under a high-voltage power line, then turn left and reach a bridge over the A13 motorway.

(5) Cross the bridge over the motorway. At the end of the bridge, turn right, still following the yellow markings. After a slight left-hand bend, turn right at a 90° angle. The marked path follows the boundary of a private property to the Carrefour de la Rouge Voie.

(6) Then turn left at a right angle. After about 600 m, at the Carrefour Henry, turn right and head downhill.

(7) After about 150 m, at a junction, continue straight ahead (let the marked path go off to the left). Descend more steeply and at the T-junction at the bottom of the Vallée des Prés, turn right. Take the^first path on the left, cross the valley and turn immediately right. Head north-east and stay at the bottom of the valley.

(8) Turn sharply left (do not go under the high-voltage power line) and follow a forest track uphill. You will come out onto the^GR®26and follow it to the left (red and white markings). Follow the edge of the plateau and ignore a path branching off to the right.

(9) Turn left before a group of houses (the hamlet of Les Guinets), still following the GR^®.

(10) At a place called l'Aventure, turn left and almost immediately right. Pass close to a drinking trough.

(11) After the Ferrières farm, continue straight ahead along the dirt track and enter the forest.

(12) At the multi-way junction (elevation 132), continue straight on following the^GR® markings^. The path begins to descend and turns left to reach the edge of the plateau, still following the red and white markings.

(13) The path veers to the right and leaves the forest. Pass close to a well belonging to the Saint-Illiers underground gas storage facility. At the junction (elevation 84), leave the markings and follow the road to the left. Pass between a small sewage treatment plant and another gas valve.

(14) Follow a path to the right that climbs into the forest (yellow markings). The winding route climbs and follows the edge of the wooded plateau. Stay on the marked path and ignore all the turn-offs to the left. Pass close to calcareous meadows.

(15) At the bottom of the descent, turn left (red and white markings). Leave the Mare du Désert on your left, ignore a path on the right and continue on the GR^®.

(16) At the Carrefour Dauphine (car park), cross the road and continue straight on. You’ll come out onto a small road; follow it to the right. You’ll soon reach the D114 at the hamlet of La Belle Côte.

(17) Follow the road to the left and after about 500 m, reach the edge of a wood. Turn right onto the path running along the edge of the forest. After skirting the field on your right, enter the woodland and descend a gradually steeper path to reach the hamlet of Apremont. Pass a wash house and arrive at a crossroads.

(18) Take the^first right, Rue du Petit Clos, and at the end, turn right twice (do not cross the railway line). Follow the^GR®26through the Vallée de la Taupe with the railway line high up on your left.

(19) Just before the end of the descent, turn left and head uphill. Pass under the railway line and climb up alongside the Ravin Gabelle. Ignore a path coming from the right, continue uphill, turn left with the path and pass the Sevestre farm.

(20) At the T-junction, turn left then immediately right onto a path between two fields. Head downhill to a junction near the church at Perdreauville.

(21) Cross a road and leave the church on your right. Head uphill through the woods and then between the fields. Ignore a path branching off to the right.

(22) At the junction with the cross-country path, go straight on (let the^GR® head off to the right). Join a path and follow it as it continues (joining the^GR®26along the way). You’ll soon reach the Chêne Mademoiselle.

(23) At the junction, turn right and you’ll soon reach the ruins of Château des Beurons.

(24) Retrace your steps back to the Chêne Mademoiselle junction.

(23) Continue straight downhill and at the junction, carry on straight ahead (no signposting). Cross the bridge over the railway line.

(25) At the end of the bridge, turn right (red and white markings). Keep going straight on along the^GR®26, ignoring all turn-offs to the left, and head downhill.

(26) At the three-way junction, turn right onto the^GR® and pass between the buildings, then under a high-voltage power line.

(27) Go under the A13 motorway bridge and continue straight on. Follow Rue Jean Jaurès; at the roundabout, turn right and you will immediately reach Rosny-sur-Seine station (S/E).

(3) A kiosk dating from the 1900 World’s Fair, decorated with mosaics, and an orientation table.

(23) Mademoiselle Oak: a very old English oak said to have been planted by Sully’s daughter to commemorate the meeting between Sully and Henry IV after the Battle of Ivry (1590).

(24) Ruins of the Château des Beurons, where Sully was born.

The heart of the Duke of Berry, a descendant of the Bourbons who was assassinated in 1820, was laid to rest in the chapel of the Château de Rosny-sur-Seine.