Urban expansion towards the hillside in the Aburrá Valley is not only due to informal housing. A high percentage of construction corresponds to the formal real estate sector, which has opted to move to the peri-urban fringe as a result of the municipal administrations' allocation of land for expansion and the economic returns that this represents.The transformation of the border has generated notorious morphological changes in the urban land due to the densities allowed, thus modifying the landscape, the social, cultural and economic dynamics and the way of inhabiting the territory in the adjacent strips or belonging to soils of environmental protection or agricultural production.