On the basis of large photometric and spectroscopic datasets, we investigated the general properties of the different sub-populations of ω Centauri in different regions of the color-magnitude diagram. In particular, we analysed the morphology, the structure and the chemical properties of the stellar populations of the system in variuos evolutionary stages. Such a large observational effort allowed us to constraint the different hypotesis on the origin and chemical evolution of this peculiar stellar system.
