The transposition of the concept of public space into a new scale, into the interior of the building, particularly within the context of a project for the development of a hybrid building, is the core issue of this investigation. The concept of interstitial public space emerges, therefore, as something within the public and the private domains. In this sense, it is imperative to examine the concept of public space, its development throughout the history of cities and its understanding in the sense of the permanent evolution of urban life style. The study of the evolution of the city and urbanism, as well as the perception and use of the public space, allows us to better understand the phenomena which characterize the contemporary city, and drives the emergence of diverse new ways of urban public space conception.
As a means of understanding the role of interstitial public space it is crucial to study the morphology of external activities, whether they are quotidian, spontaneous, intentional or unexpected, considering contemporary public space in the sense of its use. The assessment of space quality, which is by definition an interval, something that exists between different conditions and stages social interaction, undergoes inevitably the study of a non-traditional spatial structure, able to provide answers to the issues that arise in the contemporary city.
Simultaneously, the interstitial appears to us as a process of project, associated to the logic of conception though the subtraction of matter, able to generate space, as opposed to the traditional conception based on the formal relation of the different parts of the architectonic or urban object. This process necessarily results in a new typological categorization which will be defined based on the study of the types of traditional public space.
The issue of interstitial public space acquires its importance mainly in the multiplicity and functional density which nowadays characterize architecture in the urban soil, in the particular context of the centripetal city. The study of neighboring relationships and privacy issues leads us to the conception of a special element of urban character which generates itself in its own ability to organize this sort of proximity relationships, working simultaneously as a filter and drive of human activities in the private and public domains.