This article discusses the design decision-making and the post-occupancy processes of the Malagueira neighbourhood, a housing estate designed by Álvaro Siza in 1977 in the Portuguese city of Évora. In this article, I use an empirical approach supported by an ethnographic research to discuss the production of subjectivity in the Malagueira neighbourhood. In the first section of the article, I examine the extent to which ownership played an important role in the formation of the neighbourhood as a whole of singularities. Then I analyse three social-spatial conditions (patios, walls and streets) in which the design decision-making process of the Malagueira plan triggered a mediation between the ontological figures of the “one” and the “multiple”. In the following section, I discuss the immanent tension between authority and subjectivity reviewing the project’s reception. In the conclusion, I explore Antonio Negri’s ontological definition of the “multitude” to highlight how the Malagueira neighbourhood illustrates the interdependence between design decisions and processes of subjectivation in the formation of a landscape of “multiplicities”.