At the beginning of the 20th century, with the emergence of urban theories of the modern movement, the city began to be thought of from a radically new theoretical framework. The premises of this movement were based on a rationalist approach to urban design and the housing problem; the city and housing should function as a machine, so priority was given to private vehicle traffic and large tracts of land were allocated to residential use, with tall apartment towers surrounded by large green areas on the outskirts of cities (Le Corbusier's Plan Voisin or Cité Radieuse). Commercial uses, services, workplaces, administrative buildings, and cultural centers would be concentrated in urban centers (Le Corbusier, 1933).
Within this framework of the modern city, historic centers, with narrow streets, low- and medium-rise buildings, and much smaller-scale public spaces, were not considered elements of conservation interest. Here, the entire ground level would be dedicated solely to these unstructured green areas and to the circulation of private vehicles. Under these principles, large-scale urban projects have been implemented in European cities such as Amsterdam, Paris, and Rotterdam, as well as in cities in developing countries, such as Brasilia and Chandigarh. At the same time, in most North American cities, the downtown area became less attractive for residential use, and the urban sprawl expanded with low-density, exclusively residential suburbs, a pattern supported by the almost complete disappearance of public transportation and the prevalence of private vehicle use. In her book “The Death and Life of Great American Cities” (1961), Jane Jacobs harshly criticized the city model of the modern movement, which was in its heyday.
