The article examines the existing infrastructure of open common spaces within two New Belgrade mass housing blocks (Blocks 23 and 70a) through a typo-morphological analysis. These spaces between the buildings, although the most neglected, underused, and deteriorated components of mass housing neighbourhoods, are at the same time crucial to the quality, vitality and integrated governance of these neighbourhoods. They represent the primary tangible commons in cities and neighbourhoods. The question of urban commons is increasingly present in scientific literature, urban and architectural discourse. Nevertheless, approaches exploring the spatiality of the urban commons are scarce, leading to insufficient understanding of the spatial aspect and potentials of the already existing commons. Therefore, this study includes (1) identification, typological decoding and classification of the common spaces, focusing on the case of New Belgrade blocks, followed by (2) analysis of the spatial patterns and integration of the identified spaces within the blocks. The study confirms the complexity and diverse typology of the common spaces. It finds that the in-between, common spaces contribute to higher integration of different segments of the blocks. The open common spaces have an essential role in humanisation of the blocks, and thus the quality of life in the blocks as integrated neighbourhoods. The findings indicate that the spatial setting of the open common spaces in New Belgrade blocks allows for (re)emergence of collective practices, leading to inclusive and integrated rehabilitation of the neighbourhoods.