This chapter explores the historical development of salt exploitation in Europe, with a particular focus on pre-industrial salt works in Spain. For centuries, the Iberian Peninsula was a global power, benefiting from its favorable climate, proximity to the Mediterranean, and underground salt deposits from the ancient Sea of Thetis. The Salt Valley of Añana in the Basque Country, the world’s oldest active salt works with over 7500 years of history, serves as a key case study for understanding the evolution of the salt industry. Early salt production relied on forced evaporation using fire, but Romanization introduced more efficient methods, such as solar evaporation, which proved highly effective in southern Europe due to its abundant sunshine. The chapter also examines Spain’s nineteenth-century salt production cycle, analyzing different types of salt works, evaporation techniques, infrastructure construction, and salt transportation and storage. It highlights the industry’s complexity, technological variations, and the impact of state control on production costs. This state involvement, which extended to the export of techniques and production methods, is particularly relevant for understanding the Spanish Empire’s operations at the time. By the late eighteenth and early nineteenth centuries, the empire spanned vast territories, including all of South America (except Brazil), Central America, the southern U.S., Guinea, significant parts of present-day Italy (such as Naples, Sicily, Parma, and Milan), Cambodia, the PhilippinesPhilippines, and the Netherlands.