The discovery of the Saint-Jean silver vein in 1549 was the start of the “silver fever” that took hold of the Sainte-Marie-aux-Mines region in the 16th century. The Saint-Jean Engelsbourg mine was dug by hand over a length of 700 metres and a height of 500 metres. Today, a shaft over 100 metres high – called the Grande Colonne (photo) – completely emptied of its metal-bearing elements by the 16th century miners is equipped for abseiling. Three levels of descent are offered to apprentice cavers supervised by instructors: 20, 30 or 100 metres.