Abstract. The paper deals with the chances we have to use the documentary sources to obtain a better knowledge of the ancient buildings. For this purpose the paper will use, as reference, the examples of some painted decorations belonging to “modern” buildings in Genoa. The first part will be devoted to a sort of brief summary of the main categories of sources (cartographic, iconographic, written or oral). The second part aims to illustrate the researches carried out in Genoa with particular attention to: forms of contracts, decoration typologies, types of plasters, pigments. As far as it is possible the collected information is compared with the data deriving from the analysis of existing buildings