Since the Roman age the ceppo -stone was largely used in Lombardy as natural building material, especially for external covering and load-bearing structures; also for statues and carved decorations. The ceppo is a polygenic puddingstone of the Quaternary, occurring between the Olona and Adda river, north of Milan. Remarkable textural in homogeneity and variable durability/decay degree of the different facies (called rustic, me sano, gentile ) are detectable in similar exposition sites and under the same climatic conditions. They are connected with the variation of psephitic/psammitic ration, the heterogeneity of their detritic components (sedimentary, magmatic, and metamorphic in origin), the distribution of pelitic fraction, and carbonatic cement. Decay degree is valued by means of the following parameters: 1) dissolution and transformation sequences of the carbonatic cement, depending upon by the composition and distribution of the pelitic matrix; 2) uniaxial compressive, flexural, and indirect tensile strengths, decreasing up to 75% in the degraded facies; 3) water absorption weakening up to 40% the mechanical parameter in degraded samples. Noteworthy are the pore features, varying from coarse, vuggy texture to fine intertitial voids. Their measurement is difficult and less significant for testing the decay trend.