From Boissy to Brunoy via the Grange forest and the banks of the Yerres

Starting point and access: Boissy-Saint-Léger station.
- RER - Line A, terminus of one of the sections.
Take exit 1, Place de la Gare.

Yellow markings

(S) When you leave the station, follow the street to the right. After Rue Chirol (on the left), cross to the left-hand pavement. Further on, cross the Pressoirs path on the left. At the next intersection, turn left and go straight ahead at the stop sign.

No signposts

Take the^first road on the right, Rue Henri Legros. Continue along this road and ignore the access roads to buildings on the left. At an intersection (RER sidings on the right), continue straight ahead into Rue Denis Papin and enter Limeil-Brévannes.

(1) After about 150 m, at the end of the sidings and before Rue des Chalets on the left, take a gravel road on the right that runs parallel to the street. Continue straight ahead on this road, which is the platform of an old railway line. This will take you to Rue du Tertre. Follow it to the left uphill, cross Chemin Sud de Gagny on the left and turn right. At the T-junction, turn left, still on Rue du Tertre. Take the^first left, Chemin du Haut Gagny, which soon turns right. At the end, turn left into Rue Louise Chenu and immediately right into Rue du Coteau (private road, pedestrians allowed).

(2) At the roundabout, continue straight ahead and follow Rue du Tertre again, on the left-hand pavement. Go around the next roundabout on the right, cross Avenue de Valenton (D136) and take the next right after a forest barrier, Route du Grand Wirtemberg. Continue straight ahead (south-southwest) on this wide forest road. Cross a junction that forms a small roundabout and continue straight ahead along a plot of birch trees. At the next junction (altitude 92), turn left onto a stony road, the Route forestière des Bœufs.

Red and yellow markings

(3) At the crossroads (bench), take the^second path on the right, the Allée de Thésée, and head south. At the end, take the footbridge over the TGV line. Immediately turn right onto a small path that winds its way close to the TGV line. Cross a sparse forest and then an open area dominated by ferns and birch trees.

Red and yellow + yellow markings

(4) At an intersection, go straight ahead towards the Bois de Granville. Follow a path that starts at the foot of a cylindrical antenna, passes under a road bridge and immediately turns left. At the intersection that immediately follows (small information sign), turn right. Stay on the path along the fence of the TGV line. At the next intersection (beautiful beech tree in the centre), turn left and then immediately right. At the next intersection, turn left and continue to a T-junction (wall of the Château de la Grange park opposite).

(5) Turn right and follow the wall on your left (wet passages). At the junction at the corner of the wall, turn left towards Yerres-centre. Continue along the park wall until you reach a crossroads (moat on your left, information sign opposite). Take the^second path on the right, Allée du Général Lejeune, between forest plots 36 and 35. Cross a stream, cross a path, note the beautiful beech trees on either side and start climbing.

(6) Halfway up, turn left onto a fairly flat path (black arrow). Stay on the main path, which is signposted and marked with exercise equipment, and ignore all the paths branching off to the sides. You will come out onto a wide lane. Follow it to the right, climbing moderately (beautiful beech trees). When you reach a small paved area, turn left. Cross a path (not shown on the IGN map), descend and immediately reach a sandy crossroads.

(7) Then turn right. At a three-way junction that appears quickly, turn left. Wind your way through the undergrowth.

Yellow markings

Then turn right (plot no. 40) and rejoin the wide lane you left earlier (two cement slabs embedded in the ground). Then turn left and descend.

Red and yellow + yellow markings

Join the^GRP®® (coming from the left) and continue straight downhill to a crossroads (sign for the Forêt Domaniale de la Grange).

No markings

(8) Then turn left and gently descend a wide lane (again Allée du Général Lejeune). Pass a forest gate, cross a road on the border between Yerres and Crosne and follow Rue du Vieux Château opposite. Ignore a lane on the right and, when the road turns right, continue straight ahead on Sentier des Sources. Go down a staircase with a handrail and, at the bottom, continue down a street. At the bottom (numbers 71 and 73 opposite), turn left and continue on the flat. Take the^first right, Rue de la Lethumière, and go downhill. At the stop sign, go straight ahead. At the traffic lights, cross the street, follow Rue Pierre de Coubertin opposite and take a bridge over the Yerres.

Red and yellow + yellow markings

(9) At the end of the bridge, go down the steps on the left and join the bank of the Yerres. Follow the river on your left along a hard-surfaced path, the Chemin des Poètes. After two "lying" plane trees, the path moves away from the river. Shortly afterwards, turn left, cross a small wooden bridge over a stream and enter Parc Caillebotte. You will immediately come to a path. Follow it to the left and you will return to the banks of the Yerres. A little further on, turn right and take a footbridge over a pond. Then go around a pavilion on the right and continue along a gravel path. Leave the Maison Caillebotte (large white building) on your right and leave the park.

(10) At the exit, follow Rue de Concy to the left and take the Pont du 18 juin 1940 bridge. At the end of the bridge, turn left twice and go down a flight of steps. At the bottom, turn left (wash house), go under the bridge and follow the Yerres river on your right. At the start of a street, pass a small car park on your left and cross the river via a footbridge. On the other side, turn left, go through a gate and enter the Parc de l'Île Panchout. Follow a cement path, cross a footbridge over a branch of the Yerres and continue along a hard-surfaced path. Ignore a path on the right and follow the river on your left, then a lawn on your right. Cross another branch of the Yerres on a footbridge and leave the park (chicane). Then turn left to take a footbridge over the Yerres and enter the Parc des Deux Rivières.

Red and yellow markings

(11) Turn right immediately and follow the Yerres on your right. Leave the park and follow a busy road to the left. At the roundabout, turn right to cross the cycle path and the road at the pedestrian crossing in several stages. On the other side, turn right and follow a tarmac path parallel to the cycle path and the road. When you are roughly level with the park exit, turn left down a path that enters the woods. You will soon reach a hard-surfaced path; follow it to the right and cross a stream via a footbridge. At the T-junction, follow the wider path to the right. At the next T-junction, turn right and cross the stream again. At the three-way junction that immediately follows, turn left. Take a footbridge and, immediately at a fork, turn right to pass under a railway viaduct.

(12) Enter the Parc de la Maison des Arts and go straight ahead (the 1:25,000 map is inaccurate here; it is not possible to follow the river). Keep to the left of a lawn with a castle at the top. At a junction, turn right and cross the stream once more. Stay on the main path and continue to the riverbank. Pass a small kiosk, take a footbridge without railings and ignore a path on the left (not shown on the IGN map). Go through a gate, leave the park, follow a street on the right and take the old Soulins Bridge over the Yerres.

(13) At the end of the bridge, at^{the first set of} traffic lights, turn left down a hard-surfaced path, join the bank of the Yerres and follow the river on your left. Further on, the path moves away from the river. Go through a large (legal) opening in a fence, turn left and go around a lake on the right. Return to the banks of the Yerres, turn right, cross a stream and follow the river again on your left. Continue straight ahead, staying as close to the river as possible and ignoring all the paths on your right. You will come to the foot of a road bridge. Climb the steps leading up to it.

No signposts

(14) Follow the road to the left and cross the two branches of the Yerres (old mill on the left). At the crossroads, go straight ahead and up Rue du Pont Perronnet. When the street turns left, cross Place de la Mairie. On the other side, follow Rue de la Gare to the right. Then take the^first left, still on Rue de la Gare. At the end, turn right to reach Brunoy station (E).

To return home:
- RER - Line D, towards Paris or Melun.

Train timetables: consult the Transilien website.

For motorists:
Arrange to have at least two vehicles, one in the car park of each of the two stations. If you only have one vehicle, you will need to change trains in central Paris, at Gare de Lyon.

Hiking boots are useful in the forest, between (2) and (8).

Bars, restaurants and shops near the Boissy-Saint-Léger (S) and Brunoy (E) stations.

Warning:
In the event of flooding of the Yerres or threat of flooding, access to the paths along the river between (9) and (14) may be prohibited.

Public park opening hours:
Caillebotte Park:
- Opening: 9 a.m.
- Closing times: October to March, 6.30pm; April to May, 8.30pm; June to July, 9pm; August to September, 8pm.
Parc de l'Ile Panchout and Parc des Deux Rivières:
- October to May: 8:00 a.m. to 6:00 p.m.
- June to September: 8:00 a.m. to 9:00 p.m.
Parc de la Maison des Arts: 8:00 a.m. to 6:00 p.m.

Useful detailed map (at least the one accompanying this description). For tracking on a smartphone, download both the IGN and OSM maps, the latter being better suited to urban areas.

Hike completed by the author on 10 April 2022.

- Forest path between (2) and (8) with some remarkable trees and a "wild" section between (6) and (8).
- Path along the Yerres, between (9) and (14).
- Caillebotte House Museum (10).