With increasing frequency, cities are the object, through urban renewal projects, of the re-organisation of entire lots, districts or portions thereof in function of a new use of places and buildings that in the past had other uses. The more the weight of history weighs on these pre-existences, the more the interventions are conditioned by them (especially in historical centres) and, consequently, the greater is the designer's dilemma between a conservative or transformative approach. In these cases, the relationship between contemporary architecture and pre-existences cannot be separated from a series of considerations: continuity or discontinuity, scale or off-scale interventions, respect or disrespect for the context and genius loci, pros and cons in terms of the cost of the intervention, waste of land, and so on. Fortunately, there is the possibility of transformation as an opportunity to renew and regenerate buildings, spaces and places of the past in favour of the changing needs of the city and those who live in it and, at the same time, as an attempt to enhance the characteristics of the historical context and contemporary architecture in a dialectical relationship between old and new.