Deterioration of building materials due to weathering presents a long term threat to the preservation of monuments. Over several decades, intense research has been conducted to develop methods for weathering damage assessment as one step in the effective protection of both modern and historical monuments. For some time, different materials such as metals or glass, have been used to investigate weathering, but these are only capable of monitoring certain aspects of the highly complex weathering process. In an effort to provide a sensor material that can monitor the combined effects of biological, chemical and mechanical weathering, we present results of a study that examines the suitability of various natural rock types as weathering sensors. To explore the weathering behaviour, different stone types (Baumberg calcareous sandstone (BCS), Obernkirchen quartz sandstone (OKS), and marbles from Laas and Sterzing (LSM), South Tyrol, Italy) were selected and exposed at different field sites (city and high mountain area) in Tyrol (Austria) under both dry (rain protected) and wet (exposed to rain) conditions for 1.5 years. For the two city sites, the dry exposure experiments yield a pronounced correlation between air pollution and mass changes, surface structure and surface colour of the sample slabs. For the wet exposure experiments, the correlation is more complex due to masking effects such as production of sulphates and rain leaching. Preliminary data suggest that the impact of weathering on the rock types investigated is not uniform. Therefore, various aspects of the weathering process can be monitored by using different rock types as sensors.