This essay starts from the consideration that the Italian city is a physical and ideal entity, whose mostsignificant aspect is represented by its origin and the foundations of the urban space expressedthrough architecture, images and narrative expressions. The point is, for the rationalist architects, toconsider the architectural project as a physical environment in which they can manifests their deductionover the city, in which they are able to express their opinions, their interpretation and transcriptionof which is the generative idea of the city itself.To constantly give to a generative moment of the city its correct significance, means to select a specificrange of the construction and the transformation of the urban form.During the analytical moment and evaluation moment preceding the project, the architect makes a deliberatechoice to give to it of a specific position in time and a specific form of the location.The average intensity of the project for Milano green that, in some way, turn down a direct confrontationwith the existing city, allows a convincing modular switching between the two urban systemsmaking them coexist on the common settlement matrix. The city that Milano green assumes is the cityfounded on the principle of separation and distinction between buildings and their functions.On the contrary the horizontal City is a city of houses, a relatively continuous carpet of full space andempty space. A city in which predominates the green and the open space, used itself as an element toremark this ideal separation.The paradoxical dimension of the void, understood as space between things, in the Milano green istranslates into the suspended great device of the square , this was made to fix this strong idea of separation,the suspended square is a reunification with the rest of the plot.In the horizontal city the void is represented by the courtyard, from the patio of the house units, aplace of a quiet for the family, the city of the equals who identify themselves as cives, citizens.