Salins-les-Bains, a UNESCO World Heritage Treasure
Nestled in the Jura Mountains, Salins-les-Bains is home to one of Europe’s most remarkable historical sites: the Grande Saline, or Great Saltworks.
Listed as a UNESCO World Heritage Site since 2009, this extraordinary complex stands as a remarkable testament to over 1,200 years of salt production, a mineral so vital and valuable it earned the nickname “white gold.”
As early as the 8th century, the people of Salins began extracting rock salt from naturally salty spring water that rises from deep underground, not by mining, but by evaporating brine, a method unique in Europe.
The Grande Saline consists of two major historic salt-works facilities, which operated until 1962, when they were closed due to declining productivity. In 1966, the town of Salins-les-Bains acquired the site to protect this cultural treasure, which today offers a unique journey through the science and history of salt.
Rock salt, the “white gold” of Salins-les-Bains
Now you might be wondering: why is there salt in the Jura Mountains? It might seem strange to find salt deep in the mountains, but the explanation lies in ancient geology.
Around 250 million years ago, the vast ocean that covered what is now eastern France, slowly retreated, leaving behind a shallow lagoon filled with salty seawater. As the water evaporated, it deposited a 100 meters thick layer of rock salt, also known as halite. Over time, this salt layer was buried under 200 meters of marl and limestone sediments.
Then, about 35 million years ago, powerful geological forces began shaping the landscape. As the Alps formed to the east, they pushed westward, causing the land to crumple and rise, giving birth to the Jura Mountains. This intense pressure and folding brought parts of the deep salt layers closer to the surface and cracked the surrounding rocks. Water found its way through these faults, flowed through the salty deposits, and eventually emerged at the surface, creating salty springs.
This geological phenomenon gave rise to the saliferous basin of Franche-Comté, particularly around Salins-les-Bains and Lons-le-Saunier. It is from these deep underground sources that, for centuries, the people of Salins-les-Bains have been extracting salt, their famous “white gold.”
7,000 Years of salt exploitation
Salt has been extracted in Salins-les-Bains area for over 7,000 years, making it one of the oldest salt production sites in Europe. For millennia, salt was essential for preserving food, a vital resource long before refrigeration existed, and thus became a major source of wealth and power.
As early as the Neolithic period or Stone Age (10 000 BCE to 2000 BCE), our ancestors recognized the value of salt. Archaeological finds, including fortified village remains within a 7 km radius of the springs, show early settlement driven by access to salt.
Real exploitation of the brine sources began around the 5th millennium BCE, intensified during the Middle Bronze Age, and peaked during the Gaulish (Celtic) period.
In the Middle Ages, salt production brought wealth and influence to Franche-Comté, firmly establishing salt as the region’s “white gold.” The first written records of salt extraction in Salins-les-Bains date from the early 8th century.
Originally, the town had only one brine source, the future Grande Saunerie (also known as the Saunerie du Bourg-Dessus). By the late 12th century, a second facility was built: the Chauderette de Rosières, renowned for its “sel de Rosières.” Later, the Petite Saunerie (or Saunerie du Bourg-Dessous or Puits à Muire) was added.
The production method involved drawing brine (locally called muire) from wells, then evaporating the water in large cauldrons suspended above open fires. These operations required huge amounts of wood, a large workforce, and constant maintenance, particularly of a 160-meter-long underground gallery built in the 13th century to channel the brine.
From Golden Age to decline
At its height in the 15th century, Salins produced around 7,000 tonnes of salt per year. However, by the 17th century, production began to falter. The need for massive quantities of wood to fuel the evaporation process made the industry less viable, while the Ten Years’ War (1634–1644) caused widespread destruction in the region.
In the 18th century, salt production faced a new challenge: a 10% drop in water salinity reducing efficiency. Combined with the rising cost of wood and growing pressure to produce more efficiently in the pre-industrial age, profitability sharply declined. The situation was worsened by the inability to build settling basins, which could have improved productivity, due to the unpredictable flow of the nearby Furieuse River.
As a solution, a new salt-works, the Royal Saltworks of Arc-et-Senans, was built near the Chaux Forest, a vast 20,000-hectare woodland that could supply the massive quantities of wood needed. From then on, production in Salins-les-Bains continued sporadically but it was never the same.
The rise of spa culture
In the 19th century, the town of Salins-les-Bains looked to thermal therapy, as spa culture became highly popular across Europe. Recognizing the therapeutic potential of its mineral-rich springs, the town opened its first thermal baths in 1854.
Soon after, in 1864, a hotel was built to accommodate the growing number of spa visitors, followed by the construction of a casino in 1890, turning Salins into a popular destination for wellness and relaxation.
New, more modern and efficient thermal baths were inaugurated early 2017. Today, the Salins-les-Bains thermal centre welcomes more than 2,000 spa clients per year, who seek treatments for joint pain, rheumatism, trauma recovery, and growth disorders in children, all thanks to the therapeutic properties of its sodium-, calcium-, magnesium-, and potassium-rich waters. To support this thriving thermal activity, a new well, the Puits des Cordeliers, was drilled in 1994.
As for the old salt-works, now municipally managed, they no longer produce table salt but continue to provide de-icing salt for local use.
The Salt Museum was inaugurated in 2009 to preserve the town’s extraordinary history, offering visitors an in-depth look at the geological and industrial heritage of the area.
Finally, it wasn’t until 1926 that the town officially adopted the name Salins-les-Bains, highlighting both its salty heritage and its thermal future.
Wikimedia Commons: Header and Salt Museum and Interior Saline by Jean Housen is CC BY-SA 4.0 – Grande Saline and Rock salt by Arnaud 25 is CC BY-SA 3.0 – New thermal baths by Parrad.adrien is CC BY-SA 4.0 – General view of the town and Saline by Anne Daemon is CC0
