The chemical weathering of sandy limestones of a historical cathedral in Belgium was studied. Samples of atmospheric aerosols, rain water and run-off water and of the weathering crust were taken. On these samples detailed quantitative analyses were carried out, using various multi-element techniques such as ion-chromatography, atomic absorption spectroscopy, anodic stripping voltammetry, energy-dispersive X-ray spectrometry for trace analysis, and the electron micro-probe for micro-analysis and for identification of the morphological structure. -- AATA