Bray-et-Lû walks
La Roche-Guyon: the castle, the forest, the flint cliffs
Walker 
15.38 km
+384 m
-390 m
5h 30
Moderate
Departure from Amenucourt (Val-d'Oise)
A very varied hike that combines:
- Regional Forest of the Roche-Guyon,
- A beautiful, quiet valley,
- The town of La Roche and its castle,
- and finally, a scenic route overlooking the Seine.
The Dolmen of Bois Couturier
Walker 
9.18 km
+63 m
-57 m
2h 50
Moderate
Departure from Wy-dit-Joli-Village (Val-d'Oise)
The French Vexin region has numerous megalithic sites dating from the late third millennium B.C. This walk gives you the chance to visit a dolmen in a perfect state of preservation. As you stroll through the fields and woods, you will also be able to see some lovely churches and castles.
Loop around Commeny
Walker 13.37 km
+58 m
-65 m
4h 00
Moderate
Departure from Commeny (Val-d'Oise)
A straight-forward loop around Commeny passing the Perchay and Chaussée Julus Caesar.
Loop departing from Chars
Walker 10.15 km
+86 m
-87 m
3h 10
Easy
Departure from Chars (Val-d'Oise)
Walk starting from Chars SNCF station passing the Château de Saint-Cyr-sur-Chars.
On the way back to Chars there is a narrow pedestrian passage that starts with a staircase.
The Vaucouleurs valley around Dammartin-en-Serves
Walker 11.72 km
+120 m
-123 m
3h 40
Moderate
Departure from Dammartin-en-Serve (Yvelines)
A beautiful walk through stunning and varied landscapes. Historic detours along the way.
Following the Bièvre river through Saint-Quentin-en-Yvelines in Igny
Walker 
19.30 km
+20 m
-109 m
5h 35
Moderate
Departure from Montigny-le-Bretonneux (Yvelines)
The upstream part of this series of three hikes devoted to the Bièvre river. A very pleasant walk along the river and its bodies of water, in a mostly rural setting. A hike from station to station, which can be used to adjust the length depending on the weather conditions or desires of the hikers.