This article presents the results of scientific studies and examinations carried out to one of the most sever deterioration factors affecting the monumental buildings in crowded populated environment (Esna temple). This temple was built during the reign of Ptolemy V (205-180 BC.) to memorialize the god Khnum "holy local god of this region". It was built by using Nubian sandstone as a building material. In order to understand the effects of populated environment on this type of material, samples of sandstone from the temple have been subjected to some analytical techniques XRF, XRD, AAS, PL and SEM. The results proved that the temple constituents are quartz as an essential component of sandstone where, the resulted weathering products are halite, gypsum, anhydrite, niter, sylvite and kaolinite. All of them were resulted through numerous deterioration factors due to the human activities such as aggressive effects of ground waters, deliberate and un-deliberate damage, vandalism, theftting, looting. In addition to using improper conservation works and other extrinsic and intrinsic factors especially the alternative cycles between drying and wetting.