Considering that a large percentage of the population in one of the largest and most densely populated cities in the world lives in Housing Units (HU), it emerges the need of questioning and intervene the common space that generates in them. The transformation and valuation of the HU contribute to the city’s public space, where the users’ daily activities take place and where the collective needs that foster its constant change are addressed. This book is the result of the research made by Estudio de Arquitectura Rozana Montiel that approaches the interaction, resignificance and spatial rehabilitation in the HU. It gathers the concepts of the interventions made by the Estudio in multiple HU where they generated positive changes and achieved social construction from them. The publication is a succession of clues, a game of words, a glossary of motifs, a photographic archive, a method to theorize about space, a manual on how to interact in common spaces, a guide on how to read the texts and sub-texts of public space.