The study of engineering and geological properties of anthropogenic deposits, widespread in the city of Samara. Their main properties have been identifi ed and a classifi cation based on the genetic principle has been developed. The results of a petrographic study of samples from cultural layers taken at an archaeological site are presented. Archaeological excavations were carried out on the territory of Khlebnaya Square, located in the oldest part of the city, in 2019. The object represents the cultural layers that were formed in the XVIII-XIX centuries at the site of the alleged location of the second Samara fortress. Petrographic studies of the samples were carried out under a binocular microscope at 8.75 times magnifi cation, in transmitt ed light of a polarizing microscope at 72 times magnifi cation and under a digital microscope (USB DIGITAL) at 10 times magnifi cation. It has been determined that the pebble fraction is represented by quartz ite and jasper fl int, the sandy and silty fractions are angular quartz fragments with an admixture of undecomposed organic remains. The organic cultural layers, which reach 7-8 m and more in the ancient part of the city, are especially powerful. Their presence is a limiting factor in modern urban construction.

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Nowadays the area of cities is almost everywhere increasing - the territory urbanization is developing. At the same time, due to lack of land resources, the underground space development intensifi es, and the underground construction volume increases, i.e., underground urbanization takes place. This process has undoubtedly positive results, as it can help solve territorial, transport, environmental and other problems of cities while preserving the unique appearance of buildings in the historical centers of cities. At the same time, some engineering and geological processes may be activated as a negative underground urbanization result. The article deals with underground urbanization history in Samara and defi nes its main stages. More than one million people live in Samara city, subway line was built, there are subway objects of industrial and defense importance (bunkers) reaching considerable depth. Active underground construction can lead to geological processes strengthening (weathering, karst formation, suff osia, etc.), change of strength properties of rocks, violation of natural hydrological regime of the territory. The territory of Samara has an inhomogeneous geological structure and complex engineering and geological construction conditions. Seven engineering-geological districts have been identifi ed and studied, on the territory where underground construction development can lead to diff erent, including negative, consequences.