This section gathers former extraction sites converted into museums, including coal basins such as Carreau Wendel, Bochum, Blanzy, Blegny, Le Bois du Cazier, Puits Couriot in Saint-Etienne, and the Guido mine in Zabrze. It also includes the Blue Mine slate site in Anjou, the medieval Wieliczka salt mine, and the Rammelsberg mine engineering complex in Germany. These documents outline the history of underground industrial activity, explaining how sites developed from medieval origins or 19th-century expansions until their closure and transformation into preserved heritage landmarks.