Concerning the intended conservation of a Baroque construction in the center of Prague - the architectural prospectuses in the Schönborn Palace garden, the material composition of the historic exterior stucco plaster and finishing coats on this construction were analyzed. Microscopic methods, including optical and electron microscopy (SEM-EDX), thermal analyses, Raman and infrared spectroscopy, and cathodic luminescence, were used for the chemical and mineralogical characterization of historic material compounds. The mortar binder was found to be strongly hydraulic at the level of natural cement, with eminent hydraulic lime identified as the main component of the binder. The hydraulicity of the binder was further enhanced by the admixture of the crushed local siltstone. The mortar aggregate is formed from common river sand, homogenously distributed in the mortar. Clastic quartz grains accompanied with clasts of feldspar, both of them sized up to 0.5 mm, represent the sand composition. The proportion of the filler and the binder has been estimated to approx. 2:1 using the cross-sectional image analysis. Finishing layers of lime paintings on the stucco plaster were also prepared from strongly hydraulic lime. Raman spectroscopy showed that the brick-red painting layer was pigmented with hematite. No organic compounds were detected using FTIR analysis.