Transience is accepted today by the culture of design as an intrinsic quality of contemporary urban space. For the ancient consolidated European city, public space is no longer static but is the physical representation of the dynamism of interpersonal relationships and the rapid economical changes, of a society enveloped in the consumption of immaterial goods and the unstoppable construction of constantly new images. In a world dominated by “experiential marketing”, the figure of the designer is becoming closer and closer to that if the “set-designer”, called to design real urban scenographies, installations capable of updating the image of the city by changing it’s nature, albeit just for a few days a year. Public spaces see the multiplication of cultural events, expos and large meetings which require the temporary transformation of the spaces through the use of mobile and ephimeral structures, artistic installations, gardens/vegetable gardens which only have an evocative value of the natural dimension of the city, which today is completely artificialized. This transformation extends itself to the typology which changes from urban courtyard and closed boundary to a space of activity and public relations. A clear example is represented by the evolution of the Fuori Salone which has transformed parts of Milan into an enormous living room with temporary events capable of changing the nature of the districts hosting the initiatives, even in a longer lasting terms, contributing in sustaining a new identity.