The acceleration of urbanization processes leads to abrupt changes in the enviornment that can disrupt the roles of arthropods in their ecological niches. Spiders are a good model organism for studying the impact of urbanization because their development can be affected by changes in temperature, vegetation, and prey availability. The objectives of this study were: (i) to determine the number of web-building spider species, their diversity and density of their populations in urban environment. (ii) to identify the most common synanthropic species in the studied urban areas, (iii) to compare the density of spider populations in urban areas and areas with low impact of urbanization, (iv) determine population densities of Nuctenea umbratica (Clerck, 1757) in the urban areas and areas with low impact of urbanization. Spiders were collected at six locations with three different habitat types (urban habitats, suburban habitats, and forest habitats). A total of 30 spider species were identified, with Araneidae (orb-weaver spiders) showing the highest abundance and species numbers. N. umbratica stood out with the highest abundance. The increase in abundance and number of species was recorded with the decrease in urbanization. Urban habitats showed the lowest abundance and species number, while forest habitats had the highest abundance and species number. The results of this study provide a basis for understanding the impact that urbanization has on spiders in the Zagreb area.