Over time, the definitions of formal and informal city have been changed or acquired different meanings in the various fields of human activity. Since the 1950s, the industrialisation and changes in rural practices caused an accelerating mass migration of people from rural areas to major cities, which gave rise to numerous informal settlements on the peripheries of the cities. A large rural migration flows to cities searching for better living conditions. The main goal of this paper is to present the transformations that have occurred in the territory, with a focus on the peripheries of the city of Lisbon with the constructions of clandestine neighbourhoods, demonstrating through a mapping, the evolution of these informal territories in the formal city, to assess how the UAIG (Urban Areas of Illegal Genesis) developed and influenced the transformations and visions of the formal city, and the relationship that people have with the place they inhabit.

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Formal city,Informal city,Clandestine neighbourhoods,Urban areas of illegal genesis