As part of the project "Storia dei paesaggi presitorici e protostorici nell'Alto Tell tunisino", a geoarchaelogical and archaeometric study was carried out on various megalithic monuments in the region of Makthar. The general geologicl structure is correlated with the geomorfology of the territory, characterised by a cuestas land-scape. Hypotheses are formulated as to why communities decided ti live in those places (for example, the presence of water, fertile soils) and later erect megalithic monuments (for example, the quality and workability of lithoid materials) and, finally, why permanent communities abandoned the territory (that is, climatic variations or anthropic pressure). The principal lithologies of monuments and the main causes and forms of their deterioration are also described.