A two-part article deals with some historical examples of deterioration (monuments built in Dresden in 1732 had to be substantially restored and repaired 60 years later) and the actionof factors causing the decay of stone. A thorough review is given of the mechanisms of attack on stone: carbonic acid in rain water, hydraulic weathering, air poliution, biologic decomposition, water absorption, thermal influence on the behavior of the crystal constituents of the stones, as well as the moisture in the stone. Data concerning the porosity and water absorption of stones used in buildings are presented. The evaluation of the property of a particular kind of stone as a suitable building material is discussed. Frost damage occurs only when the pores of the stone are filled more than 91% with water.