This article delves into the phenomenon of informal settlements in the outskirts of Medellín, with a specific focus on the case of the Lenin or Francisco Antonio Zea IV Etapa barrio de invasión between 1969 and 1975. It examines the historical context, the factors that contributed to the establishment and growth of this informal settlement, and the impact it had on the surrounding community. The article also analyzes the official response to the issue, including the government's policies and initiatives aimed at addressing the problem of informal settlements in Medellín. Furthermore, it discusses the social, economic, and environmental consequences of informal settlements, and the challenges they pose to the city's development. By exploring the case of Lenin or Francisco Antonio Zea IV Etapa, this article provides valuable insights into the complexities of informal settlements and their implications for urban planning and policy-making in Medellín and beyond.