Antonio Vázquez de Castro embodied a lifelong engagement with socially driven architecture, balancing visionary experimentation with pragmatic, low-cost solutions deeply rooted in the material and human context of each project; shaped by childhood memories of the Spanish Civil War, his early sense of adversity translated into a firm ethical drive that found its first major expression in the Caño Roto social housing development in Madrid, where he not only designed but also lived during its construction, embodying a direct and participatory form of architectural responsibility; alongside José Luis Íñiguez and Joaquín Ruiz Hervás, he developed typologies that prioritized dignity and adaptability for working-class families, an ethos he later exported to Latin America through the PREVI project in Peru, under the impulse of architect-president Belaúnde Terry, where low-rise, high-density models challenged dominant paradigms of urban growth in the Global South; an exemplary case is Tabibloc, a modular prefabrication system with vibro-pressed concrete blocks that could be transported in a trailer, which he used for his own home in Aravaca, proving its domestic and sustainable potential, though its industrial future faltered after the death of a key partner; his broader legacy includes landmark projects like the Reina Sofía Museum with its iconic glass elevator towers, the central pavilion for the 1992 Seville Expo, and urban plans for Palma and Vallecas, always marked by clarity of structure and civic generosity; as professor, director general, and progressive voice during the transition from dictatorship, his influence was also institutional, most notably through the strategic redirection of public art funding to revitalize theatres across Spain, setting a precedent for cultural investment as architectural policy; Vázquez de Castro leaves behind a rare synthesis of technical ingenuity, political acumen, and social conscience, reminding us that architecture, at its best, can be both shelter and statement.