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 – Great Saltworks.
A UNESCO World Heritage Site since 2009, this extraordinary salt-works bears witness to over 1,200 years of salt production, a mineral so precious it was nicknamed “white gold.”
As early as the 8th century, the inhabitants of Salins extracted rock salt from naturally salty springs gushing from deep within the earth, not through mining, but by evaporating the brine, a method unique in Europe. The Grande Saline comprises two large, historic salt-works, which operated until 1962, when they closed due to declining productivity.
In 1966, the town of Salins-les-Bains acquired the site to preserve this cultural treasure, which today offers a unique journey through the history and science of salt.
Rock salt, the “white gold” of Salins-les-Bains
You might be wondering: why is there salt in the Jura Mountains? The presence of salt deep within the mountains may seem strange, but it’s explained by ancient geology!
Around 250 million years ago, the vast ocean that covered what is now Eastern France slowly receded, leaving behind a shallow lagoon filled with salty seawater. The evaporation of this water deposited a layer of rock salt, also called halite, up to 100 meters thick. Over time, this salt layer was buried under 200 meters of marl and limestone sediments.
Then, around 35 million years ago, powerful geological forces began to shape the landscape. During the formation of the Alps to the east, the pressure exerted westward caused the terrain to fold and uplift, giving rise to the Jura Mountains. This intense pressure and folding brought parts of the deep salt layers closer to the surface and fractured the surrounding rocks. Water seeped through these fissures, permeated the salt deposits, and finally gushed to the surface, creating salt springs.
This geological phenomenon gave rise to the Franche-Comté salt basin, particularly around Salins-les-Bains and Lons-le-Saunier. It is from these deep underground springs that the inhabitants of Salins-les-Bains have extracted salt, their famous “white gold,” for centuries
7,000 Years of salt exploitation
Salt extraction in the Salins-les-Bains region dates back more than 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 the invention of the refrigerator, and thus became a major source of wealth and power.
As early as the Neolithic period (10,000 to 2,000 BCE), our ancestors recognized the value of salt. Archaeological discoveries, notably the remains of a fortified village within a 7 km radius of the springs, attest to an early settlement motivated by access to salt. The actual exploitation of the brine springs began around the 5th millennium BCE, intensified during the Middle Bronze Age, and reached its peak during the Gallic (Celtic) period.
In the Middle Ages, salt production brought wealth and influence to Franche-Comté, making salt the region’s “white gold.” The first written records of salt extraction in Salins-les-Bains date back to the early 8th century.
Initially, the town had only one brine source, the future Grande Saunerie (also known as the Saunerie du Bourg-Dessus). At the end of the 12th century, a second facility was built: the Chauderette de Rosières, renowned for its Rosières salt. Later, the Petite Saunerie (or Saunerie du Bourg-Dessous, or Puits à Muire) was added.
The production method consisted of drawing brine (locally called muire) from wells, then evaporating the water in large cauldrons suspended over open fires. These operations required enormous quantities of wood, a large workforce and constant maintenance, including of a 160-meter-long underground gallery built in the 13th century to transport the brine.
From Golden Age to decline
At its peak in the 15th century, Salins produced approximately 7,000 tons of salt per year. However, production began to decline as early as the 17th century. The need for wood, necessary for evaporation, made the industry less profitable, while the Ten Years’ War (1634-1644) caused significant destruction in the region.
In the 18th century, salt production faced a new challenge: a 10% decrease in water salinity, thus reducing efficiency. Combined with rising wood prices and increasing pressure to produce more efficiently in the pre-industrial era, this decrease led to a sharp drop in profitability. The situation was exacerbated by the impossibility of constructing settling ponds, which could have improved productivity, due to the unpredictable flow of the nearby Furieuse River.
To remedy this, a new salt-works, the Royal Saltworks of Arc-et-Senans, was built near the Chaux forest, a vast 20,000-hectare forest capable of supplying the considerable quantities of wood needed. From then on, production at Salins-les-Bains continued sporadically, but it was never the same again.
The rise of spa culture
In the 19th century, the town of Salins-les-Bains embraced thermal bathing, as the practice of spa treatments was experiencing considerable growth in Europe. Recognizing the therapeutic potential of its mineral-rich springs, the town opened its first thermal baths in 1854. Shortly after, in 1864, a hotel was built to accommodate the growing number of spa clients, followed by the construction of a casino in 1890, making Salins a popular destination for wellness and relaxation.
New, more modern and efficient thermal baths were inaugurated in early 2017. Today, the Salins-les-Bains thermal centre welcomes more than 2,000 spa-goers each year, who come to be treated for joint pain, rheumatism, injuries, and growth disorders in children, thanks to the therapeutic properties of its waters rich in sodium, calcium, magnesium, and potassium. To support this important thermal activity, a new well, the Puits des Cordeliers, was drilled in 1994.
As for the old salt-works, now managed by the municipality, they no longer produce table salt but continue to supply road salt for local needs. The Salt Museum was inaugurated in 2009 to preserve the town’s remarkable history and offer visitors an in-depth look at the region’s geological and industrial heritage. Finally, it was only in 1926 that the town officially adopted the name Salins-les-Bains, thus highlighting both its salt-making heritage and its future as a thermal spa.
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
