The physical and chemical interaction of water from ground seepage, precipitation, or condensation on the walls is the main factor in mobilization of soluble salts. The pressures produced during crystallization are then comparable with those during freezing of water within the pores. Because the crystallization cycles (and hydration-dehydration cycles) are much more probable in comparison with freezing-thawing cycles in the Middle Europe climate, the salts seem to be the principal cause of decay of monuments. -- AATA