The Royal Saltworks at Arc-et-Senans is a historical salt production facility located in the town of Arc-et-Senans in eastern France. The saltworks was built between 1775 and 1779, during the reign of Louis XVI, and was designed by the French architect Claude Nicolas Ledoux.

The saltworks complex is notable for its innovative and functional design, which was intended to maximize efficiency and minimize waste. The facility features a circular design, with buildings arranged in a concentric pattern around a central courtyard. The buildings include a number of features such as chimneys, flues, and pipes that allowed for the efficient production and processing of salt.

The saltworks ceased operation in 1895 and was subsequently converted into a cultural center and museum. Today, visitors to the Royal Saltworks can explore the various buildings and exhibits that showcase the history and significance of salt production in the region. The saltworks was designated a UNESCO World Heritage site in 1982, and is considered a significant example of 18th-century industrial architecture.