Le Sentier des Maréchaux, the educational forest walk in the Chevreuse Valley

The Sentier des Maréchaux is an accessible trail in the heart of the Vallée de Chevreuse, an immersive stroll through the former sandstone quarry at Senlisse. Information panels provide valuable insights into the quarry's geology, history and local flora and fauna. This 4.1 km-long trail offers an hour's instructive stroll through the quarrying culture of the early 20th century, and a fascinating insight into the historical workings of the region.

The Sentier des Maréchaux starts at the Parking des Maréchaux, with a well-marked entrance from the route des Franchises between Senlisse and Les Essarts-le-Roi. You can, of course, stop at the first parking lot at the entrance to the forest, but you'll have to walk for over a kilometer to reach the start of the trail. As you venture into the forest, however, you'll need to pay close attention to the many potholes along the way to the parking lot.

At the trailhead, a signpost provides an initial introduction to what lies ahead. It's also an essential reference point for orientation along the way. Nature is generous and, after a few minutes' walk, we're greeted by the sight of the first quarry. This historically rich quarry was in operation until 1930, and the sandstone extracted from it was used to build sidewalks.

Continue along the path and the forest opens its arms, with a landscape reminiscent of the Fontainebleau forest thanks to the pine trees and white sand of a large sand quarry. The path leads us through several other quarries, whose remains silently recount the history of the region. This is where the sandstone used to make the famous Parisian cobblestones was quarried !

If you can't tell the difference between naturally eroded blocks of stone and the remains of the quarry, or between black alder and white birch, don't worry. Information panels along the way help visitors understand the geology, history, quarrying techniques and local flora and fauna.

In particular, you'll discover that the site's workers enjoyed 8 to 10 days' paid annual leave, which was exceptional in the 19th century. However, their working conditions were extremely difficult, with the result that most did not live beyond the age of 60.

Along the way, traces of sandstone quarrying can be seen, as well as an old drinking trough used to quench the thirst of the animals working on the site.

The exploration continues with the discovery of millstone quarrying, which bears witness to another facet of the Valley's industrial history. We learn about the use of millstone in the construction of single-family homes in the Paris region.

The abbey wall is another notable station on the trail. It marks the way toCernay Abbey, a site of undeniable historical richness. As well as being a spectacular site, the estate offers visitors a choice: retrace their steps, continue on to the Cernay waterfalls or visit the abbey.

As you follow the Sentier des Maréchaux road, you come across strangely shaped sandstone boulders reminiscent of certain areas of the magnificent Fontainebleau forest. On the descent, you come to a marshy area which then leads to the Etang de Cernay and its superb natural setting.

A monument to Léon Germain Pelouse stands on the edge of the pond. This little-known name is actually that of a landscape painter (from the Barbizon school) who enjoyed a certain renown. Several of his works are on display at the Musée d'Orsay, for example.

The Sentier des Maréchaux is not just an educational trail, it's a journey through time, an ode to nature and a reminder of the industrial history of the Vallée de Chevreuse. With each step, the valley reveals a little more of its essence and secrets. The walk, pleasant and rich in discoveries, ends on a note of appreciation for the region's natural beauty and historical heritage.

This looping trail is more than just a stroll, it's an experience that educates, informs and fascinates, allowing everyone to connect in a unique way with the history and nature that surround the Vallée de Chevreuse. And we have to admit, during our hike at the end of September, beginning of October, we took the opportunity to pick chestnuts and mushrooms, without really looking for them. A great way to combine business with pleasure.

• To be read
• Tips for the week of January 27 - February 2, 2025 in Paris: free or inexpensive outings
• Free Museums and Monuments to visit in Paris and the Ile-de-France region, good ideas for outings

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