The modern city is an important social and cultural-spatial entity, within which events from various spheres of human life take place. These events affect not only the development of society but also the general state of ecology. In contrast to rural areas, in cities, the urbanized environment prevails over the natural, so the formation of the city’s ecological infrastructure is an extremely important issue. The article considers various types of environmental initiatives that have found their practical application in the architecture and construction of libraries. The study is focused on successful examples of ecological library functioning in different regions of the world. The essence of the study is to highlight the important role of the library, which it plays in the formation of environmental awareness of society. Along with this, the article emphasizes the growing attention to ecological library buildings and their potential to change the face of the modern city in terms of sustainable development.