<p>Morphological and geochemical characterization of the particulate depositions collected from the surfaces of urban monuments located in two Mediterranean cities characterized by high levels of atmospheric particulate matter (PM), namely Thessaloniki in Greece and Nicosia in Cyprus, was carried out using multiple analytical techniques. The geochemical composition of bulk samples was found to be dominated by CaO and SiO₂ with lower proportions of Al₂O₃, Fe₂O₃, and MgO suggesting influence from local and/or transported dust (road dust, Saharan dust). The effect of traffic was evident on the sides of monuments oriented towards busy roads with higher concentrations of anthropogenic elements such as Zn, Ba, Cu, V, and Ni. Gypsum was detected in a few samples only and is possibly attributed to sulfation process and/or windblown Saharan dust. Notably, a wide spectrum of low- and high-molecular-weight organic compounds was also detected (aliphatic hydrocarbons and organic compounds containing carbonyl- and carboxyl-groups, urea and nitrogen-containing biomass, amino acids, fatty acids and lipids, plant residues, synthetic polymer residues, and combustion products) suggesting the presence of various natural and anthropogenic sources. The results obtained in the study may serve as a guide for the development of appropriate strategies for protection and conservation of the urban architectural heritage in the two countries.</p> Graphical Abstract <p></p>