Did you know that a 36-ton mill can almost spin on its own? That’s the hallmark of the Moulin de Sannois, perched on Mount Trouillet in the Val-d’Oise. On September 19 and 20, 2026, the Heritage Days provide an opportunity to take a closer look at this remarkable relic of rural life in Île-de-France. This annual event highlights monuments, buildings and crafts that are sometimes little known, giving the public a better understanding of their history and how they work.
The tale of the current mill begins in 1759-1760, when François Roger, a vintner from Franconville, had it built on the hillside. He wasn’t alone: Mont Trouillet once hosted up to three mills. With the arrival of the railway and the rise of large industrial flour mills in the 19th century, activity gradually waned. The Town of Sannois took ownership of the mill in 1938 and launched several restoration campaigns to safeguard it.
And thankfully, because its mechanism deserves a look. The Moulin de Sannois is a pivot mill, or a chandelier mill. Unlike mills where only the cap turns, the entire wooden cage can pivot to face the wind. Its central beam, about five hundred years old, rises six meters high, while its wings reach a 22-meter wingspan. It is today presented by the City as the only pivot mill in Île-de-France still in operation.
Inside, the winder, gears, and imposing millstones tell the story of the old millers’ craft. When the wind is strong enough, the mechanism still demonstrates how wind energy was converted to grind grain and produce flour. Listed on the supplementary inventory of Historic Monuments since 1975, the mill is today preserved and promoted by the City of Sannois. Guided tours help convey its history, while also highlighting a know-how that long formed part of rural life in the Île-de-France region.
Guided tour of the 18th-century pivot mill
During European Heritage Days, the city of Sannois is offering guided tours of its mill. A post mill built in 1759, it is today the last of its kind still in operation in Île-de-France. On this tour, you’ll delve into the mill’s history, its construction and its use in flour production, and its surprising transformation into a guinguette at the start of the 20th century.
Participation conditions: Tours depart at the top of every hour, with the last tour at 6:00 PM. Groups are formed on site and limited to 25 people. - Free | No reservation required
Hours: Saturday, September 19, 2026, 2:00 PM – 7:00 PM | Sunday, September 20, 2026, 2:00 PM – 7:00 PM
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Dates and Opening Time
From September 19, 2026 to September 20, 2026
