This paper studies the notion and content of constitutional space, its integral parts and components, key features and principles in order to help identify the spatial limits of state power and provide efficient legal support to integration processes. To articulate the multifaceted concept of constitutional space, the author has analyzed the approaches of a number of Russian and international researchers which allowed him to trace how this concept developed from the fl at territory-bound format to a valuecentric three-dimensional presentation or so-called 3D format. The purpose of this paper is to define the concept of constitutional space, its content and role in the context of state building aimed at ensuring territorial integrity, unity of the Russian system of law and more efficient use of the mechanisms provided by federal agreements based on the analysis of scientific information sources and constitutional norms.