The royal saltworks of Arc-et-Senans, listed in 1982, was the work of Claude-Nicolas Ledoux, architect and saltwork inspector for Franche-Comté and Lorraine. Construction started in 1775 and was completed in 1779 during the reign of Louis XVI. This visionary architectural project of a “model factory” was the first example of large-scale industrial architecture and reflects the ideal of progress of the Age of Enlightenment. It was the new and utopian extension of the large saltworks of Salins-les-Bains, which was included in the listed site in 2009.
The outstanding character of this property relates in part to the specific nature of salt production at Salins-les-Bains and Arc-et-Senans, based on a technique of tapping deep salt-water sources, the use of fire to evaporate the brine, and the innovative creation of a 21-km-long pipeline in the 18th century to carry the brine between the two sites. The saltworks of Salins-les-Bains and Arc-et-Senans are also remarkable for the length of time that salt was extracted at Salins, at least from the Middle Ages and probably from pre-historic times, up to the 20th century. The spa continues to be used today.
Criterion (i): The royal saltworks of Arc-et-Senans w as the first architectural complex of this scale and quality designed for human industry. It was the first factory to be built showing the same care and concern for architectural quality as a palace or major religious edifice. It is one of the rare examples of visionary architecture: the saltworks was at the heart of an Ideal City that Claude-Nicolas Ledoux had imagined and designed around the factory. While this utopian vision was never realized, the saltworks still bears its forward-looking message.
Criterion (ii): The royal saltworks of Arc-et-Senans bears witness to a fundamental cultural change in Europe at the end of the 18th century: the birth of industrial society. It is the perfect illustration of a philosophical movement that swept through Europe during the Age of Enlightenment; it also heralds the industrial architecture that developed half a century later.
Criterion (iv): The saltworks of Salins-les-Bains and Arc-et-Senans constitute a remarkable technical ensemble for the extraction and production of salt by pumping underground brine and the use of fire for its crystallization, operating since at least the Middle Ages and up to the 20th century.