Biotic and abiotic world interacting with the city life is the subject of the text, which sets up from an introduction regarding the role of gardens in the city and in the citizens’ life. It clarifies dynamic natural phenomena interfering with cultural built environment. Biotic ecosystems and abiotic components (water, air, soil, etc.) in the city are analyzed and interpreted as complex habitat condition. Various concepts are proposed aimed at enhancing the new frontiers of the environmental consciousness among people and actors, while modification in the cultural character of a city are taking place. Examples of integration of Green Infrastructures as important biotic element for the increase of Natural capital in the city are identified and critically investigated. Last but not least the role design plays on land, mainly architecture, as science which collaborates to the definition of built areas in an urban milieu in which, indeed, plants, animals and men interact, is underlined, as far as some technical aspects are concerned. For example the employment of natural-based materials, both within the pre-industrial and traditional architecture, and the industrial innovation products, which can aid to put again together nature and humans
