The research subject of the present thesis, is the highlighting of the importance of the in-between space, as a place capable of managing the transitions and relationships between spaces. The research examines various attempts to define the concept of “in-between” in Humanities, as interpreted by various theoretical scientists. Through the approaches, different versions and features of the in-between space emerge, that connect with the other spaces.

Then, through bibliographic research, the group that introduced the concept in architectural theory is presented, and through the typical example of the Municipal Orphanage in Amsterdam designed by Aldo van Eyck, the design principles of the implementation of the idea of the in-between space are explained.

In the third chapter, a deepening of the concept is done by conducting an on-site investigation in various parts of the city of Volos, and specifically in Nea Ionia, in order to categorize the examples based on the architectural design and the experience of the spaces from the user's point of view. It is interpreted how the housing practices applied by the residents, in order to “own” the space, give identity to the urban gaps and in the public spaces.

In the fourth and final chapter, reference is made to the pandemic of covid-19, that has recently changed the design data. Keeping people indoors for a long-time redefined design principles in both the private and public spaces. The in-between spaces, which were often not utilized at all, acquired identity and use. People's daily lives changed and it was expected that this change would overturn both architectural theory and practice.