The rescue excavation of the Marais du Colombier site, Varennes-sur-Seine (Seine-et-Marne) enabled us to study a rural establishment dating back to the first half of the 3^rd century BC set in a damp low-lying area of the plain situated in the lower reaches of the Seine/Yonne confluence. The establishment, structured around an empty area interpreted as a courtyard or horticultural space, has nearly all the components of a rural establishment: dwellings, granaries and other annexed buildings, silos, wells and ditches. Among the buildings, the dwelling was notable for the adoption of an oval plan probably supporting the hypothesis of a roof structure, which makes it one of the most ancient of the Iron age. Of the many macro vegetal remains, preserved in several pits, the main one being 5003 situated near the house, enabled a palaeobotanical analysis. The combination of archaeological, archaeobotanical (carpology, anthracology, xylology) and archaeozoological data enables a reconstruction of a surrounding environment marked by its great diversity and exploitation (plants cultivated, collection environment, livestock farming, hunting). All the elements combine in this agricultural establishment to reveal a production unit providing a comfortable level of life. Its organisation is rather different from that of the most part of the early La Tène period and from the beginning of middle La Tène of the Senonais area and seems to prefigure that of the enclosure sites of the middle and late La Tène. As for the presence of human remains, they bring elements on the funerary practices connected to children dying at a young age and on cultural practices in a domestic context.