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Start point: Thun-le-Paradis station (Transilien line J – Paris Saint-Lazare / Mantes-la-Jolie branch via Conflans-Sainte-Honorine).
No signposting
(S/E) On leaving the station, turn left onto Rue des Annonciades. Just past the houses, go down the steps on the left, cross the bridge over the railway line and continue to Rue Gambetta. Cross the street, turn right then immediately left onto Rue Nicolas Leclerc, and continue to Quai de l’Arquebuse.
(1) Head towards the banks of the Seine, take the path on the right to follow the river for 3 km, until you reach Mézy-sur-Seine, where the path leads to a car park at Place du Port aux Foins.
(2) Turn right onto Rue du Port, then cross Avenue Chateaubriand before heading up Rue du Château on the opposite side. Walk past the town hall, then head up Rue Erambert. Take the narrow Ruelle Souillard on the left, which leads onto Avenue du Général Charles de Gaulle. Head up the opposite side via Route d’Apremont, then take the path on the left facing Chemin des Mottes. Walk uphill alongside the houses.
(3) Note the viewpoint with the orientation table on the left. Join Rue d’Apremont, turn right and continue to the corner of the property and its Villa Paul Poiret.
(4) Take thefirst path on the left, which leads further on to Route d’Apremont. Continue in the same direction. At the entrance to Juziers, take the Vieux Chemin de Mézy on the right, then turn right onto the Chemin des Sablons, which, once in the forest, becomes the Chemin d’Apremont to Oinville. Pass the reservoir and continue straight on until the second junction.
(5) Turn left, then right about a hundred metres further on to follow the Chemin des Nivingt Prés, which continues as the Chemin de Saint-Laurent.
GR® white and red markings
(6) Carry on straight ahead along the GR®. Atthe second junction, turn left onto the Route de la Chartre. Turn right onto the road, pass under the high-voltage power lines, and carry on straight ahead, letting the GR® branch off to the left.
PR® yellow signposting
(7) Take thefirst path on the right, into the field. At the road, turn left towards the hamlet of La Chartre.
(8) After the Étang des Poiriers, turn right onto the Chemin des Joncs. Atthe third junction, take the track on the left and continue straight on to cross the Bois des Brise-Pic and join the Rue de Gargenville (D130) at a memorial stone.
(9) Turn right, then cross the D130 to follow the path which climbs to the left past a picnic area, followed by houses. At the viewing platform, take the steps opposite, then continue straight on to Rue de la Carrière, which leads down to a car park. From this point to (11), there are information boards about the Battle of the Vexin in 1944.
Off the marked route
(10) Take the path opposite, which overlooks the sports grounds. At the next two Forks in the road, turn left. At the crossroads in the middle of the fields, follow the path straight ahead which goes uphill and, at the T-junction, turn left. Walk past the Saint-Laurent farm, join the road and continue to the junction.
GR® white and red markings (new route)
(11) Turn right to enter the Moussus-Saint-Laurent Departmental Wood. Continue straight on until you reach the junction where the GR® turns sharply left.
No signposting
(12) Leave the GR® and continue straight on. Follow the path downhill, exit the woodland onto a grassy area and head towards the edge of the fields. Turn right, then left at thefirst junction. Continue straight on to rejoin the GR® directly beneath a medium-voltage power line.
GR® markings: white and red
(13) Turn right, then enter Fontenay-Saint-Père. Stay on the same street, pass the town hall, then carry on straight ahead.
(14) Shortly after the junction with Rue de Montgison, look out for the entrance gate to the Clos des Tilleuls on the left: a good spot for a picnic. Carry on straight ahead, going round the church on the right. Turn onto Rue Pasteur, then turn left onto Rue de Mantes to join the D983.
(15) Cross the road with care, walk up alongside the road, then take thefirst path on the right which runs alongside a field before entering the woodland. At the junction with the GR®11, carry on straight ahead along the GR®2 until you reach the edge of the woodland.
(16) Turn right along the field, then head down thefirst path on the left. Halfway down the slope, at the blue marker, take the path on the left. Join the Chemin des Venises, then continue left onto Rue Jules Ferry. Go round the church and head down to the right via Rue Wilson. Follow the GR® signposts towards Mantes until you reach the junction with Rue des Lavoirs. Head back up the path opposite, known as Chemin de la Grenouillère, until you reach Rue du Maloret.
(17) Turn right, join the path that leads into the woodland, then continues in a wide curve to the left before joining a tarmac road. Head up to the left along the Chemin de la Pleigne. Pass a path on the right and reach a Fork in the road. Take the Chemin des Groux on the right, as far as a house.
(18) Turn right at a right angle onto the Sente de la Pleigne, which, after winding its way through fields and woods, enters the forest. Follow the GR® markings carefully until you reach the edge of the forest, at the Chemin de Saint-Sauveur.
(19) Head down to the right along a footpath and a few steps. Take Rue des Roussettes on the right, then head down thefirst footpath on the left to reach a wide road, Rue du Docteur Vinaver. Cross at the pedestrian crossing on the left, turn right then left onto a footpath that leads to the banks of the Seine and the towpath.
GRP® yellow and red markings
(20) Turn left to walk alongside the Seine as far as the road bridge between Limay and Mantes and the D983a.
White and red GR® markings
(21) Cross the road, keeping the bridge on your right, and head down the opposite side between the row of trees and the houses. At the T-junction, turn right and cross the Seine via the footpath/cycle bridge linking the two sides of a former bridge, which was opened on 20 July 2026. On the opposite side, join a wide footpath, keeping the car parks on your right. Turn right onto this path and, after a left-hand bend, you’ll reach the second pedestrian and cycle footbridge over the Seine. Cross the river again towards Mantes. Once on the other bank, continue straight ahead on the same pavement until you reach the Collegiate Church of Notre-Dame, which stands on Place Jean XXIII.
No signposting
(22) With your back to the collegiate church, cross the road and follow Rue Porte des Comptes straight ahead to Place Saint-Maclou. Cross the square to the tower of the same name.
(23) With your back to the tower, take Rue des Arigots. Then turn left onto Rue Notre-Dame. Continue straight ahead along Rue Porte Chant à l’Oie. After the car park, turn left.
(24) At the gate, enter Square Gabrielle d’Estrée. Walk across the square towards the buildings, then turn left towards the exit. Take Rue Gate-Vigne on the right, until you reach Rue d’Alsace. Turn left, then immediately right onto Rue Chanzy. Take thefirst street on the left, then thefirst on the right, and finally go straight on to Square Brieussel Bourgeois, passing the Town Hall on the way.
(25) Walk along the left-hand side of the square, then turn left towards the Pavillon Duhamel, the town’s former museum. Leave the square via Rue l’Évesque, turn right onto Rue de l’Évesque, then take the narrow lane immediately on the left. Then turn left onto Rue de l’Yser, then right onto Rue Saint-Lazare to reach a main road.
GR® red and white markings
(26) Take Boulevard Victor Duhamel on the right, then continue straight on until you reach the railway line. Walk to Mantes Station: take the Transilien line J towards Paris Saint-Lazare (E).
Visorando Member
Moderate 
Easy 
