In this thesis, the long-term weathering behaviour of five important natural stone varieties under atmospheric conditions is examined. Besides "Carrara" and "Laaser" marble, the Lindabrunner conglomerate as well as the limestones from St. Margarethen and Aflenz were studied. Their use in historical architecture, whether as building stones or ornamental stones, is widespread in the Central European region. In the autumn of 2003, the natural stones were placed in a courtyard of the “Mauerbach” monastery to investigate their weathering phenomena under exposed conditions. This thesis provides the results of a first state record 14 years after installation and shows the weathering progress of the stones whose composition simulate different exposure conditions, that could be found on most structures. The following methods were used in the investigation: Nondestructive methods: 1. Ultrasonic velocity testing 2. Electrical conductivity measurements 3. ^Surface temperature measurements Invasive methods: 1. (Thermo-) gravimetric moisture testing In addition to a detailed discussion of the results, the problem of nondestructive insitu testing is also highlighted. Comparison of the relative conductivity measurement with the more precise gravimetric moisture testing, with different climatic boundary conditions, is intended to provide information about the usability of the data. Furthermore, references are made to possible influencing factors in the ultrasonic velocity testing. The results of the ultrasonic measurements show that there is a clear disaggregation of the microstructure in each of the exposed natural stones. A clear dependence of the disaggregation rate on the nanoclimatic situation on the respective lithotypes is evident. In the course of the ultrasonic testing, interesting conclusions were drawn on the influence of the boundary conditions. ^Results should serve as an impulse for further studies in the area of measurement methods. The comparison of relative and absolute moisture values illustrates the uncertain nature of electrical conductivity measurements.