The sector of Dampierre-Maincourt is located in the Vallée de Chevreuse, near Sain-Quentin en Yvelines, above the river Yvette.
Access 1 : for the main sector, park the car along the D58, in the center of the village of Maincourt, go down Le Chemin du Moulin and turn right at the GR11. Cross the river at an old washhouse and continue on the GR for 300m. The first boulders are above in the thalweg (start of the children's circuit) and, by going up and right, the starts of the yellow circuit PD and blue circuit TD- can be found (as well as the 30 last numbers of the orange circuit and the end of the red one).
For the sector of La Butte Ronde, park the car at the bottom of the well-known cyclists' 17 bends on the D91 and follow the GR for 400m. The starts of the orange and red circuits are above in the slope, after the path has turned left and then right.

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