In 2002, a very important Middle Palaeolithic site has been discovered at the base of a tufa sequence overlying an alluvial formation of the Lower Terrace at Caours (Somme basin). From 2005 to 2010 excavations have produced a unique superimposition of four in situ archaeological layers separated by sterile tufa deposits (more than 10 600 large mammal remains and 3 200 flint artefacts). U/Th dating (average: 123±3 ka) and the bioclimatic studies demonstrate that Caours tufa records the Eemian interglacial in the Somme basin. The malacological fauna shows a succession from Lateglacial to Interglacial environments and the climatic optimum (MIS 5e) is identified by both large mammals and molluscs. Mammalian assemblages are dominated by species of temperate climate and woodland landscape (Cervus elaphus, Dama, Bos primigenius). Bones show numerous cut-marks and a huge proportion of pieces have been fractured for marrow extraction. This site gives a unique opportunity to study Neandertal’s lithic production systems in a temperate environment. The analysis of the artefacts shows Discoïdal and Levallois technologies within the oldest level whereas the three others are characterised by Discoïdal flaking leading to the production of pseudo-Levallois points and backed flakes. The raw material has been extracted from the gravels of the terrace. The refits show that some flakes have been taken away from knapping places to the butchery areas to be used as knifes. The study of the lithic assemblages is thus consistent with the archaeozoological results showing that Caours corresponds to a butchery site. Fireplaces, marked by concentrations of burned bone fragments and heated flints, have also been evidenced. The four archaeological levels discovered at Caours represent a unique example of Neandertal occupation during the Last Interglacial in Europe. Finally, this study demonstrates that Neandertal populations were adapted to forested full interglacial environments.