The Fond-de-Gras is a small valley where have been numerous mining galleries. A railway line connected this valley with a town called Pétange. Thanks to this railway line, the iron ore was forwarded to the ironworks in Luxembourg and abroad.
From the last quarter of the 19th century, several concessions were granted to very active societies in Fond-de-Gras. These societies constructed warehouses, workshops and offices. Nowadays it is very difficult to imagine this small valley as one of the most important mine sites in Luxembourg until the 1960s.