In the west of the department of Gard, at the foot of the Aigoual, about an hour from Nîmes, Montpellier, Alès, Millau, Florac... and 5 km from Vigan, here is Bréau-et-Salagosse with the village of Beam built on a hill, while Serres and Salagosse, the most important hamlets, are built in the valley. Its territory extends from the South to the North, from 267 m to 1373 m of altitude on 2500 hectares, of which a part in central zone of the Cévennes National Park, in the heart of the biosphere reserve. It benefits from the Mediterranean climate and the sunshine of the south. Olive and chestnut trees in the south on schistose, beech and coniferous soils in the granite massifs in the north.
Mars is located on an old passageway descending from the Mouzoulès pass to the Coudoulous valley. The village has preserved a traditional habitat in hamlets with its houses built of granite and shale. It is crossed by several streams which water the numerous vegetable gardens and the orchards arranged on the slopes and in the bottom of valley.
