From Arpajon to Saint-Chéron via the Bassin de Trêvois and the Château de Baville

Starting point and access: Arpajon station.
- RER - Line C, on the section between Paris and Dourdan.
Take the Place de la Gare exit on the side of track 2 (Dourdan to Paris direction). If arriving in the opposite direction, track 1, take the underground passage.

No signposts

(S) When you leave the station, cross the square and walk down Avenue de la République. At the first intersection, turn right onto Rue du Docteur Louis Babin. At the next intersection, turn left onto Rue Roger Lhuillier. At the end, turn right.

(1) After about 30 metres, turn left onto Rue Marcel Duhamel and cross the Orge river. Walk along a car park and continue along a paved path beside a small river (the Boëlle).

(2) At the end, first turn right then left to cross the river on a wooden bridge and enter a park. At the fork, turn right. Take the first wooden bridge on the right to cross the Rémarde. You will come out onto an avenue; follow it to the left and pass under the N20 bridge.

Red and yellow markings

(3) At the stop sign, go straight ahead on Route d'Arpajon and enter Ollainville. At the next stop sign, continue straight ahead along the wall of a property (narrow pavement).

(4) At the next stop sign, turn left onto Rue de Saint-Arnoult. Turn right onto this street and walk alongside the buildings of the Syndicat de l'Orge (water treatment plant). At the end of a car park, there are two gravel paths: take the one on the right and climb a flight of steps.

No markings

(5) Continue straight ahead (ignore the arrow pointing to a wooden bridge on the left). After a short stretch of tarmac, follow a track and walk along the Rémarde on your left.

Yellow markings

(6) At the end, cross the road at the pedestrian crossing and follow it to the left, taking a cement path that runs parallel to it.

Yellow + red and yellowmarkings

(7) At the foot of the sign marking the entrance to Égly (wash house on the left), turn right and go through a forest gate. Follow the Orge river on your left. Shortly after passing a hut, you will reach the eastern end of the Bassin de Trêvois.

Blue markings

(8) Continue straight ahead and walk along the lake on your right. Pass a geometric wooden sculpture on your left.

No markings

(9) About 1.2 km after the eastern end of the basin, turn right to briefly reach the small menhir called Pierre Beaumirault. Retrace your steps.

Blue markings

(9) Continue along the main path, which makes a series of first turns right then left, then right.

(10) At the end of the second right turn, turn left onto a footbridge. You will come to a road; cross it and follow it to the left onto a shared path for pedestrians and cyclists.

(11) At the crossroads, turn sharply right onto Route de Guisseray. Continue straight ahead through a residential area. On the right-hand side, you will see an old industrial chimney and a wash house on the Rémarde river.

(12) Come out onto the D116 and follow it to the left. After about 100 metres, turn right to cross the road at the pedestrian crossing. On the other side, first turn left then right onto Allée de la Chouette to reach the entrance to Parc du Colombier (where you can visit and take a break).

(13) Turn left, go through a forest gate and continue along a path between a wood on the left and the park fence on the right. Go through another forest gate and continue along Rue de Malassis. At the end, turn right into Rue de Courte Pluche.

(14) After about 50 metres, turn left onto Rue du Bois Veti. Soon, the tarmac gives way to a path. Pass through a forest gate and continue straight ahead into the woods. Further on, pass through a second gate. You will come to a small road; cross it and follow it to the right.

(15) After about 30 metres, turn left onto a wide gravel track. Walk alongside horse pastures on your right. Pass a riding centre, go through a gate and continue straight ahead (ignore a yellow arrow indicating a left turn). Further on, go through another gate.

Yellow markings

(16) Cross a small road and continue straight ahead on a paved path. Walk along the left-hand side of the grounds of Château de Baville, which you can see in the distance. Continue straight ahead, slightly uphill, and ignore a path on the right. Turn left onto the paved path.

(17) At the "Tour Gabrielle" marker, continue straight ahead on the paved path. Further on, rejoin the tarmac road, walk alongside the Petit Baville housing estate and ignore a small lane on the left.

(18) At the crossroads, follow a path that slopes diagonally to the right. You will come to a paved section and then, at the top of the hill, another path. Continue along the tarmac road (Rue Bouillon Lagrande) and descend towards the church, which is clearly visible. At the traffic lights, turn left and leave the church on your right.

No signposts

(19) At the T-junction that immediately follows, turn left. Pass a small square on your left and, shortly afterwards, turn right into the narrow Ruelle Pajadon. Descend between two walls. Pass a chicane and continue straight downhill. At the bottom, turn right and cross a car park to quickly reach Saint-Chéron station (E).

To return home:
- RER - Line C, towards Paris (immediate access) or Dourdan (take the underground passage).

Train timetables: consult the Transilien website.

For motorists: Arpajon and Saint-Chéron stations are on the same section of the same line: park in the car park of one of the two and make a return trip by train.

Hiking boots are useful.

No water sources identified along the route. Bars and restaurants in Arpajon and Saint-Chéron, particularly near the stations.

A detailed map is useful (at least the one accompanying this description).

Hike completed by the author on 14 February 2026.

- Pleasant walk along the river.
- Trêvois basin, between (8) and (10).
- Baville Castle, between (16) and (17).