Analytical investigations were carried out on alteration crusts of "Pietra d'Istria" used for the construction of "Palazzo Papadopoli" in Venice. The chemical and mineralogical analyses of the microstructure showed that alteration process in mainly caused by the transformation of calcium carbonate into calcium sulphate and that the greatest damages are due to the subsequent detaching of sulphatic crusts according to a weakness surface. The isotopic analyses showed that sulphur present in the crust is mainly derived from the combustion of hydrocarbons. The investigations on the climatic conditions showed the meaningful importance of the climate parameters on described alterations.