Starting point: Foyer Rural, 27 Rue des Vaux de Cernay.
(S/E) On leaving the car park, head right for about 150m until you reach the Jardin de la fontaine du Roi.
(1) Turn right onto a path that runs alongside the Ru des Vaux. Then climb a few steps to reach the D73. Turn left towards the church. Continue straight ahead along Rue Grande Rue, ignoring the side streets, until you reach Place de la Mairie.
(2) Turn right and continue along Rue du Perray-en-Yvelines.
(3) Take the Sente de la Gâtine on the right. Turn left (gate). Walk down to a T-junction. Continue down the slope to the right until you reach another T-junction.
(4) Turn left onto the GR®1C. Further on, cross a road and walk past a sewage treatment plant, then a drainage channel on your left. After the ‘bean-shaped’ part of the pond, take a sharp left towards a flight of steps leading to the Étang du Perray.
(5) At the top, turn left, with the pond on your right. At the end of the dyke, go through a gate and immediately turn left to cross a small bridge. Cross a road and walk along the ditch on your right until you reach a Fork in the road (marked by an information sign reading “La rigole de coupe gorge”).
(6) Turn left and follow the path to the D61. Cross the road carefully and continue to a crossroads.
(7) Just before a barrier, turn left. Cross the D73 carefully and pass under a high-voltage power line. Cross the D61 again and take a small path marked in blue and white. Further on, cross another road and continue straight ahead for about 250m.
(8) Turn left, go through a gate and follow a wide path until you reach the first houses in Les Vindrins.
(9) Turn immediately right. Then immediately right again onto a small path (look for a ‘CHEMIN’ sign on an electricity pole). Ignore two paths branching off to the left. At the Fork in the road that comes up straight away, head right and ignore the side paths to come out onto a sandy track. There are three conifers in the middle of this. Go to the right of them and then climb a small slope.
(10) Continue until you reach a car park on your left. Head south across the second small sand pit, passing behind a shelter on your left. Continue straight ahead through the woods. At the junction that comes up quickly, go up to the right. Cross a junction, then at a fork turn left (south-east).
Blue and white markings
(11) At the next junction, head diagonally left, then turn right at the following junction until you reach a T-junction. Walk a few metres to the right.
(12) Turn left (look for a sign for the ‘Route de Saint-Benoît’) until you reach La Tuilerie.
(13) Continue slightly to the left. At a Fork in the road, turn left.
End of the blue and white markings
(14) Head diagonally left (look for a sign for “Abbaye des Vaux de Cernay”). Take this path, which descends quite steeply at first, until you reach the D24. Cross it with care. Continue to the left, go through a gate and cross a small bridge.
(15) At the corner of a wall, take a path on the left which runs alongside the Abbaye des Vaux de Cernay and then its pond. Continue to a crossroads.
(16) Let the GR® head off to the right and follow a small path opposite. Ignore two small paths leading uphill to the right. At the Fork in the road immediately ahead, turn right. Ignore the small side paths. Further on, head left to see the Grandval bridge. On the way back, take the first path on the left. Carry straight on for about 650m.
(17) Continue left along the GR® path, which you’ll rejoin here, all the way to Auffargis. You’ll come out onto Rue des Vaux de Cernay; turn right to quickly reach the car park on your right (S/E).