La Ville du Bois, Nozay, Rocher de Saulx, Villejust

The starting point is near the Bois des Échassons in Longpont-sur-Orge. You can park on Allée des Charmes or in the primary school car park (Rue André Chermette).

(S/E) Head north until you reach the Allée du Château de Villebouzin.

(1) Opposite the château, take the lane on the left towards the N20. Cross the main road and head up Rue des Cailleboudes on the opposite side. Take the^first right (Voie des Postes) until you reach the traffic lights. Turn left onto Rue du Grand Noyer, then take the^first right onto Chemin de la Croix Saint-Jacques. At the end of the cul-de-sac, take Chemin du Bois de la Turaude.

(2) Turn left to head up towards Chemin de la Turaude. At the top, turn right (onto the^PR®) and carry on to the ‘Stop’ sign.

(3) Carry on to the right for about a hundred metres, then turn left onto the Chemin des Sablons and head towards a wooded area on your right. Set off opposite it along the Chemin de Saint-Éloi, continue along the grassy path, cross the Route de Nozay and you’ll reach the start of a path on the right.

(4) Turn right into the Bois de Monsieur (yellow markings) and then into the Bois de Saint-Éloi (they are right next to each other). After the timber storage area, take the path on the right to head up towards the far end of the woodland. Once at the top, turn left and carry on until you reach a road (Chemin du Gros Chêne).
Freestyle enthusiasts will find plenty to enjoy in this woodland, with several trails reserved for mountain bikes. The paths in this woodland are very muddy in winter or in wet weather.

(5) Turn left and take the^{second path}on the right (Chemin des Lièvres) at the corner of the second built-up area. This path is blocked at the end, so you’ll need to veer slightly to the right before crossing it again at right angles (towards the Gros Chêne). A lovely descent takes you to the end of the Chemin des Auvergnes.

(6) Turn right straight away, walking alongside a private fence. The Voie des Roches is quite a steep little climb! Follow the route (^PR® – yellow markings) until you see an old quarry on your right.

(7) Turn left at the quarry and head towards Chemin Neuf. Walk for about 160 m, then turn left down the Mort Rue (stream). Be careful! Don’t miss the path on the left which will allow you to retrace your steps and complete a circular route.

(7) Carry on straight ahead towards Nozay. Cross Chemin Saint-Pierre and take the unmarked path opposite (though it is clearly defined). You’ll eventually come back onto Chemin du Gros Chêne; turn left and, as you emerge from the woods, continue across the fields.

(8) Walk through Nozay via the town centre (town hall and church), along Rue du Gros Chêne and then Rue des Pylandries. You can stock up on supplies here.

(9) Turn right onto Chemin de la Poupardière, leave the village and walk alongside the Alcatel/Nokia complex. At the end of the complex, take the path on the right. When you reach the road, first turn left then right and continue along the path until you reach the woods.

(10) Go round the edge of the woods on the right, keeping to the edge, then turn left and follow the power lines to the riding centre. Head diagonally to the right and reach the Rouillon stream.

(11) Cross the little bridge over the Rouillon, then head uphill towards Villejust. When you reach the top, carry on uphill to the right, then rejoin the path on the right, towards the Bois du Rocher de Saulx. At the end of the path, head up to the left and, at the top, turn right (^GR®).

(12) At the T-junction, turn right and carry on straight ahead almost all the way to the car park.

(13) Turn right to complete a circular route around the rock. The paths here are lovely, easy to walk on, wide and shaded. It can get quite busy with walkers on Sundays.
Carry on straight ahead and, when you reach the track, retrace your steps.

(12) Leave the route you’ve already taken and carry on straight ahead until you rejoin the^GR® after the^second left-hand bend.

(14) Turn right and head straight down to the D118. Cross the road and walk past a riding centre (Bois des Gallaines). Just after this, and before a junction, take the small road on the left and head towards the first junction a few metres past the sign marking the entrance to the town of Villiers.

(15) Take the small road that climbs to the left (with a wall on your right), then continue along a track. The climb isn’t very steep but it is long: pace yourself!
When you reach the top at Villejust, cross Rue de Saulx (Route de Villejust), walk past the cemetery and turn left. Follow Rue des Papillons and look for the start of a footpath just past the sports grounds on your left.

(16) Take the path on the left which goes round the Papillons estate and then turns left. After a lovely descent (a bit tricky with all the stones and rocks…), cross the track you took on the way out and head towards the Rocher de Saulx. Carry on straight ahead, staying on the main path which runs alongside the Couloire and the Milans at the foot of the Rocher de Saulx, which is on your right. Alternative route: those keen for a bit more of a challenge can climb back up by taking one of the paths leading up to the right; there’s always the option to come back down afterwards.
Follow this path straight on until you reach Rue de Lunezy at the entrance to Saulx-les-Chartreux.

(17) Turn left and head to the first junction with a small road on the right. Carry on straight ahead along the grassy path opposite (with rocks in the middle to prevent vehicles from passing), cross the Saulx plain and, at the end of the straight stretch, turn left onto the cycle path and go under the N20.

(18) Carry on straight ahead, passing through Ballainvilliers down Rue de Longjumeau. At the roundabout, turn right onto Rue des Peuliers, then at the next one, carry on straight ahead onto Rue du Petit Ballainvilliers. After the Clos du Château housing estate, turn left onto Avenue du Château, then right onto Rue des Écoles.

(19) After Les Serres de Balain, where you’ll see two high-voltage electricity pylons on your right, take the grassy path that leads uphill to the left, cross the Route de Chasse (D186) and head back down towards Longpont-sur-Orge. Cross Rue du Perray and carry on straight ahead. Warning! You are going the wrong way; dismount and walk for 100 metres. Use the pavement to avoid putting yourself in danger.
Continue along Rue André Chermette and head for the school car park or the Allée des Charmes after crossing the small Bois des Échassons on the left (S/E).

(S/E) You can head down to the centre of Longpont to see the Basilica.