The characterisation of physical properties of existing substrates represents one of the most important survey activities preceding any intervention aimed at consolidation, strengthening, injection and even non-structural work on historical objects. The strength of the substrate is usually investigated for an assessment on the degree of degradation and the efficiency of consolidation treatments. The modulus of elasticity and the Poisson ratio are important for mathematical modelling of materials. Natural stones are assemblages of one or several types of minerals. Unlike solids like metals, glass or synthetics, stones are non-uniform and sometimes also anisotropic systems. Similar to the natural weathering of rocks, the deterioration of stone in sculpture and architecture is a complex process, and much of the knowledge achieved in the respective disciplines of geological engineering can be used to understand the causes and mechanisms which seriously threaten our cultural heritage.