Cariocas MultipliCities: a term that synthesizes and highlights the vast and diversified urban, cultural, and social landscape of the city of Rio de Janeiro. The Carioca spirit promotes the idea of integration and coexistence, where mixing is seen as a source of vitality and richness for the city. This essence, which embraces and celebrates its Multiple Cities, makes Rio a truly unique and captivating place. The central theme of the work was the impact of Rio s Urban Public Spaces of Coexistence – UPSCs on citizens well-being and quality of life, with the proposal to encourage understanding of their importance. The need to consider Urban Space as a territory for Design intervention was addressed, as well as the relevance of periodically revisiting projects. The theoretical framework delved into how the agents involved in urban projects conceive the city beyond the act of designing, identifying gaps between theory and practice. The contribution of Participatory Design in this process was presented, emphasizing the importance of transdisciplinarity in understanding complex systems such as cities and societies. The work addressed the difficulty in conceiving and implementing these spaces, highlighting the importance of community involvement from the initial stages of the design process. The development and evaluation of effective strategies for the implementation of participatory methodologies in the initial stages of projects, aiming at creating solutions that authentically reflect the demands of local communities, was the main point of investigation. But how to enable effective popular participation in decisions related to UPSCs? Participatory research methodologies related to Ergonomics in the Built Environment – EAC are tools with great potential to positively guide the initial diagnosis phases of projects, focusing on citizen and sustainable perspectives, that is, solutions that are sustainable in the long term. Through a mixed methodology, Co-creation Workshops were conducted with two distinct groups. The workshops with users used the Place Diagram as the main analysis tool, while the workshops with specialists used Envisioning Cards. These tools were selected, adapted, and applied with the intention of promoting collaboration and innovation in the search for effective solutions. This collaborative approach aimed to promote the exchange of ideas among different perspectives, enriching the quality of the collected data and providing a more holistic understanding of the urban issues under study. The research achieved its objective by demonstrating that through co-creative dynamics and participatory methodologies in small-scale contexts, we can engage the community and obtain data that contribute to understanding existing challenges and guiding old and new local projects. The collected data were compared and analyzed to identify patterns and new ideas that could validate the research hypothesis that if we apply participatory methodologies in local communities, we can articulate knowledge that contributes to urban diagnosis phases and guide more effective project actions. The results also confirmed the research problem regarding the challenge of implementing participatory methodologies in the preliminary stages of UPSC projects that enable solutions based on the desires and demands of their local communities. The work offered an important methodological contribution, highlighting the advantages of combining quantitative and qualitative methods to understand complex environments. Additionally, it suggested ways to improve the methodology, such as integrating specialists and users into collaborative activities. It is recognized that cities are composed of a variety of socioeconomic, cultural, and geographical profiles, and that a flexible and adaptable approach is necessary to meet the needs of all citizens. I believe that public spaces should be inclusive, accessible, and able to reflect and meet the varied needs of a diversified population. I perceive the City of Rio de Janeiro as a living organism in constant evolution, composed of Multiple Cities that connect and form this vibrant and inspiring a City that is Multiple.