Annotation text. Setting the problem is a transition from the analysis of the street from the point of view of exclusively technical design or scenario, to the street as an element of the urban ecosystem. This will give impetus to the formulation of new indicators of sustainable development. Publications related to the transformation of the central streets of historical cities mainly cover individual components of sustainable development systems or are limited to purely theoretical issues regarding the design of the urban environment. At the same time, most consider the issue of the street as a transport artery, not a public space. The aim of this publication is to define and justify the principles of transformation of the downtown streets of cities with the further development of the appropriate methodology, which should combine all three directions of sustainable development - ecological, economic and social. The novelty of the publication consists in tracking the types of transformation of the downtown streets and formulating the principles of transformation of the streets in city centre. Methodical approaches and methods of transformation of downtown streets depending on various components of sustainable development - ecological, economic and social - have been revealed. It was found that the implementation of the above-mentioned principles can be achieved by changing the functional and planning organization of the street, as well as by transforming the subject environment with the help of landscaping elements - stationary, non-capital and landscaping elements. The transformations should ensure the sustainable and prospective development of the street, comfortable conditions for work, transit and recreation of people, optimal parameters of the street for transit and temporary preservation of transport. In further research, the authors intend to analyze the compliance of the tasks of sustainable development in the restoration of urban ecosystems with the identified principles of transformation of central streets and to formulate new indicators of sustainable development.