Preservation of our Historical Cultural Heritage built in stone requires studies on the material itself, on the environment where the monument is located, and even on the microclimate affecting a particular stone in the building. The knowledge of the decay processes, as well as mechanisms governing these processes, and the real effect of factors depending on the intrinsic properties of the material to be studied, and external agents of decay, will allow a rationale use of these materials and to anticipate their behaviour beforehand, in order to success in restoration.