From Ballancourt to La Ferté-Alais, the Itteville marshes and the Sanglier rock

Starting point and access: Ballancourt station.
- RER - Line D, on the section between Paris and Malesherbes.
Take the Rue Eugène Péreire exit, on the side of platform 2, travelling from Malesherbes to Paris (if arriving in the opposite direction, platform 1, use the underpass).

Yellow + Red and White markings

(S) On leaving the platform, at the level crossing, turn left twice and follow Rue Eugène Péreire. Ignore the road on the right at the^first junction and pass a metal bridge on the right, fitted with old railway tracks.

Yellow markings

(1) Immediately afterwards, leave the street and turn right onto a grassy path along the Essonne. Ignore the^first footbridge on the right and take the^{second one} to cross the river at a small dam. Immediately turn left onto another footbridge over a tributary and enter Parc Christian Imbert.
N.B. A sign reading “Park closed due to dangerous weather conditions” appears to have been left there permanently (it was there on the day of the walk, even though the weather was fine and stable). Please take note depending on actual conditions.
Turn left, passing a ping-pong table on your left. Go through a forest gate and turn left, cross the Essonne again and leave the park.

(2) Turn immediately right onto a grassy path along the river. After about a hundred metres, take a small lane on the left (house no. 13). At the end, turn right onto a small tarmac path which soon bends left. At the Fork in the road that appears immediately, turn right between a wall and a hedge. You’ll come out onto a lane; follow it to the left.

Yellow + Red and White markings

At the stop sign, turn right and follow Rue Eugène Péreire again with the^GR®11C. Keep going straight on.

Yellow markings

(3) At the junction, follow the D74 to the right towards Itteville. Cross two branches of the Essonne in succession and enter Itteville via the Route de Ballancourt. Climb the hill and pass the Itteville drinking water plant. At the junction by a high-voltage pylon, follow the D31 to the left towards La Ferté-Alais. After about 150m, as you approach a cycle path, cross the road (with care) and follow a farm track due west (marked by a small rock at the start). At the end, turn left. Ignore the access path to the pumping station on the left. Then take the^first path on the right and follow a fenced-in meadow on your left.

Blue markings

(4) At the end (small car park and hiking map on the left), follow the Route de Saint-Vrain to the right. Shortly after passing the Impasse de l’Évangile on the right, turn left onto a grassy path that descends between gardens.

Blue + Yellow markings

At the bottom, turn left onto a wide path and walk alongside a wetland area on your right.

(5) At the junction just before a gate on the left, turn right towards the Blongios observatory (forest barrier). Follow a path between the pond and the reedbed to reach the observatory (no entry beyond this point). Retrace your steps.

(5) Continue to the right (south-west) along the wide path and note the church of Itteville high up on the left. At the next junction, turn right and pass a hairpin bend (follow the^PR®65and let the^PR®57go straight on). Walk alongside a fenced meadow on your left. At the T-junction, turn right to quickly reach the Avau observatory. Retrace your steps and, at the previous junction, continue straight ahead (west-south-west) between the fenced-off meadow on your left and a pond on your right.

(6) At the crossroads, take the^first path on the right to reach the Aigrettes observatory. Retrace your steps.

(6) Continue south on a wide path. Pass through a metal gate.

Yellow markings

Ignore the track branching off to the right, pass a hiking map on your right and continue south. Cross the Chemin de l'Enfer on your left and, at the junction immediately ahead, turn right onto Rue Saint-Germain. Cross Rue à Jacques on the left and, at the triangular square (crossroads), turn right. At the next junction, follow Rue de la Porte de Bouray to the right. Come out onto the D449 and follow it to the right for a few metres, until you reach the pedestrian crossing.

No signposting

(7) Cross the D449 and first turn right then left to follow the small road running parallel to the D449. At the Fork in the road that appears shortly afterwards, turn left onto Chemin du Mocquetonneau (tarmac). Stay on this small road and ignore all the paths branching off to the left. At the end of the tarmac, continue west-north-west along a grassy path. Walk alongside a copse and note the menhir of La Roche à Gentil in a field on the right.

Blue + Yellow markings

(8) At the T-junction, turn left. At the next junction, continue straight ahead, veering slightly to the right. Walk alongside a small fenced-off plot on your left and continue between the fields. At the end, follow the path to the left. Ignore a turn-off on the left, then one on the right, and enter a wood. Climb slightly, stay on the main marked path which gradually narrows, and ignore the turn-offs on either side.

Yellow markings

(9) At the crossroads, continue straight ahead (south-west; ignore the blue markings on the left as well as the yellow markings of another^PR®). Ignore a path branching off to the right, leave the woodland and continue for about a hundred metres along the edge. Continue between the fields, ignore a path branching off to the right, then turn left at the foot of a double-sided yellow sign. Enter a wood and arrive at a three-way junction after a few dozen metres.

No markings

(10) Then turn sharply left. Leave the woods and continue along the edge of the woods on your right. After a slight bend to the left, at a junction, take the path on the right that leads into the woods. Ignore a path branching off to the left (not shown on the map) and continue south-southeast. Walk alongside an old sand quarry below on the left. After a bend to the left, ignore a track on the right and head due east. Note the boulders on the right and you will reach a crossroads.

(11) There are then two options, both of which are compatible:

- Off the beaten track and off the path, to the right (south), there is access to the Sanglier climbing site, which can serve as a picnic spot – Take care: some rocks are very mossy (and therefore slippery in wet weather); it is sometimes necessary to make long jumps from one rock to another, and you must watch out for sheer drops.

- Continue the walk – Two clearly marked paths lie ahead: take the path on the right (east-southeast) downhill. The slope is steep and the path zigzags through the undergrowth. You’ll come out onto a small road; follow it to the right, still going downhill but more gently. Leave the woods and you’ll reach a crossroads (yellow double-sided sign).

Blue + Red and White markings

(12) Then turn left (east-southeast) onto a path that runs between the fields towards another double-sided yellow sign (note a large shed in the distance on the right). When you reach the shed, ignore a path branching off to the right. At the next junction, continue straight on along a hedge. At the end of the path, continue along a small road that soon turns right. At the Stop sign, cross at the pedestrian crossing and follow the main road to the left for a few dozen metres.

(13) At the crossroads, turn right onto the D449 towards La Ferté-Alais. Cross the road as soon as possible (take care) and use the pavement on the left to safely pass a section with no pavement on the right-hand side. Cross the Essonne one last time and enter La Ferté-Alais. When the D449 turns right towards Malesherbes, continue straight on along Rue Eugène Millet.

No signposting

At the next junction, turn right onto Rue Augustin Bellard. Then take the^first right, Rue de l’Essonne. At the end, turn sharply left into the narrow Rue de la Gatine. At the end, turn right again onto Rue Augustin Bellard. At the next junction, turn right onto Rue du Dôme and you will arrive at the entrance to the church in La Ferté-Alais.

(14) Then turn left into Place du Château. Turn left at the west end of the church and continue straight on. Cross Rue Sainte-Barbe then Place du Marché. At the end, turn right then left into Rue du Cygne.

Red and white markings

At the junction (note the beautiful nursery school building opposite), turn right and rejoin the^GR®11. Head uphill and walk along Place Sadi Carnot on your right (column with a bust of the former President of the Republic). At the next junction, continue straight ahead. At the traffic lights, go straight on and take the bridge over the railway line.

Red and white + yellow markings

As you leave the bridge, turn left onto a tarmac path running parallel to the railway line below. After about 200m, take the footbridge on the left which leads to the platforms at La Ferté-Alais station (E).

To get back home:
- RER - Line D, towards Malesherbes (platform 1) or Juvisy and Paris (platform 2).

Train timetables: see the Transilien website.

For motorists:
Both stations are located on the same section of the same line. It is therefore possible to leave a vehicle at either station and make a one-way or return journey by train. N.B. The car park at La Ferté-Alais station has limited capacity, so it is likely to fill up quickly on weekday mornings.

Hiking boots are required.

A 1:25,000 map is required (at the very least the one accompanying this description). A compass may be useful for finding your way around the Sanglier area.

Facilities along the route:
- Toilets at the exit of Parc Christian Imbert.
- Bars, restaurants and shops in the town centre of La Ferté-Alais.
- Market on Saturday mornings in La Ferté-Alais.

Warning:
The former Ardenay sand quarry, near the Rocher du Sanglier (11), is used for trial riding. In theory, the motorbikes stay within the quarry and you shouldn’t come across them on the route you’re taking. However, this activity causes noise pollution, making it difficult to stop for long in the area. I have found no information regarding the times when this site is used for trial riding (on the day I undertook this ride, there were no motorbikes on site). If you wish to avoid this area at all costs, see an alternative route below.

Alternatives:
- Avoiding the Sanglier area - At the three-way junction (10), continue straight ahead following the yellow markings. At the next junction, turn left (ignore the markings turning right). At the junction about a hundred metres further on, turn left onto the^GR®11(red and white markings). Rejoin the main route at the point (12) (go straight on).
- Avoiding a detour through the town centre of La Ferté-Allais - After the point (13), at the junction with Rue Augustin Bellard, continue straight ahead on the^GR®. Rejoin the main route at the next junction, the Carrefour du Cygne (go straight ahead).

Hike completed by the author on 6 April 2019.

- A pleasant walk along the Essonne from (1) until just after (2).

- Itteville Marshes, between (5) and (6). An area of ponds, reed beds and wet meadows, designated a Natura 2000 site. Three observation points around the edge of the pond allow you to watch the birds. The wet meadows are maintained through eco-grazing by Bretonne Pie Noir cattle.

- La Roche à Gentil, one of the most imposing menhirs in the Île-de-France region, standing 4 metres tall and weighing 20 tonnes. The menhir stands in an open field and is therefore inaccessible up close when crops are growing, but it is close enough to the path to be clearly seen.

- Former Ardenay sand quarry, before (11).

- The Sanglier rock formation (11). A climbing spot rarely visited by climbers, which is suitable for a break or a picnic.

- Church of Notre-Dame de l'Assomption (12th century) (14).