The region of the Central Alentejo is a peneplain drained by the Rivers Tagus, Sado and Guadiana and enclosed by the relatively low hills of Serra de Ossa, Serra do Mendro and Serra de Monfurado (Figure 2.1). Geologically it is composed of granites or related rocks and schists (or similar metamorphic rocks); some tertiary patches are still perceptible, along with a zone of carbonated rocks (marbles and dolomites). In administrative terms, the Central Alentejo coincides more or less with the present area of the District of Évora.