Marsal’s existence is built on salt. The village in Saulnois, (German: Salzgau) on the tiny River Seille was created on top of a pile of broken clay. Around 1000 BC brine from salt ponds was dried in clay pots; the resulting cakes of salt were knocked out of the pots, the remains of which were thrown on a waste heap. An estimated 4 million cubic metres of broken clay covers the area, and this is all due to the so-called "briquetage" technique. Nowadays there is no longer any trace of salt production in Marsal. Salt-loving plants still flourish on the ground, whereas salt-loving people prefer to pay a visit to the local Salt Museum.

Everything is tasteless without salt. Even the mighty demanded this precious mineral. It is therefore no surprise that salt works and ramparts were constructed in the village of Marsal on the command of the Bishop of Metz as early as the 13th century. The clergy fought over the salt with the aristocracy. In 1663 a military architect by the name of Vauban took control of Marsal on the orders of the Sun King, Louis XIV. Whereas Moyenvic, Chateau-Salins and Dieuze still continued to produce salt, in 1699 Marsal was transformed into a garrison town with seven bastions of soldiers until a part of the site was razed to the ground in 1870.

The Salt Museum in Marsal comprises both military and technical history. In the "Porte de France", the oldest town gate, erected by Vauban alongside the barracks, replicas of a salt oven and the "briquetagen" (coarse ceramic vessels) show visitors how salt cakes were dried out in clay pots. The museum follows the path of salt from its discovery to its final disappearance through the tiny hole of a salt cellar. Anyone eager to know more should retrace the path along the ramparts of the town to the “salt pond”. Here you can discover the remains of military buildings and the Saint-Léger monastery.