It was also connected with saltworks of Salins-les-Bains (added in an extension to World Heritage Site in 2009) by a 21 km pipeline carrying the brine.

This led the experts of the Ferme Générale to consider exploiting even small springs, an initiative that the King's council stopped in April 1773.

On September 20, 1771, Louis XV appointed Ledoux Commissioner of the Salt Works of Lorraine and Franché-Comté.

This gave him an opportunity to see many different saltworks, including those at Salins-les-Bains and Lons-le-Saunier, and to learn from them what one might want if designing a factory from scratch.

Two years later, Madame du Barry supported Ledoux's nomination to membership in the Royal Academie of Architecture.

(He was already the architect for the Ferme générale, the private customs and excise operation that collected many taxes on behalf of the king, under 6-year contracts.)

In his own critical review of the project, Ledoux stated that he had put too much weight on the conventions of a factory to the neglect of symbolic aspects.

The result was a flat, uniform design based on bi-lateral symmetry, rather than one that would have a marked center of gravity.

The design also recalled the traditional communal buildings of the time such as convents, monasteries, hospitals, large farms, and the like.

Furthermore, since ancient times, architects had recognized that plans such as Ledoux's were vulnerable to the spread of fire and not very hygienic, with throughout the day some part of the site being in the shade.

Other buildings on the semicircle include on the left, as one faces the entrance, quarters for carpenters and laborers, and on the right, marshals and coopers.

Then, during October 1939, at the outbreak of World War II, the French military installed an anti-aircraft battery in the courtyard area.

Still, February 20, 1940, saw the publication of the official announcement of the classification of the salt works and its surrounding wall as historical monuments.

From May 1941 to September 1943, the French authorities established an internment camp to hold the area's gypsies and others with no fixed address (Centre de Rassemblement des tziganes et nomades).

After the war, there was an extensive public campaign by artists, journalists and writers from the region to encourage the authorities to protect the site.

[5] The Saltworks were a primary location in the 1961 film by Pierre Kast La Morte-Saison des amours AKA The Season for Love.

In 1965, Marcel Bluwal used the director's house for the tomb of the Commander in his television adaptation of Molière's Dom Juan.

Since 1973, the royal salt works and the Institut Claude-Nicolas Ledoux have been members of the European network of cultural sites.