The rehabilitation of historical centres in Italy offers a vast quantity of experiences, though the concept of preserving urban and architectural heritage is quite recent. In fact the same experience does not find place for industrial districts or areas. The scale of intervention is specific to each case as it deals with single artefacts as well as complex building systems, open spaces and urban closeness. The heterogeneity of adopted methods is a result of diverse contextual conditions and, perhaps above all, diverse urban policies. An initial distinction must be made between Monument and Document, thus distinguishing two levels, both equally relevant to the preservation of the identities of a site, though of widely varying origins and – quite often – diverse physical, formal and functional consistency. This text will examine primarily those aspects related to urban morphology, looking at buildings by means of the Vitruvius paradigm: firmitas, utilitas and venustas. These notions will, however, be subordinated to superior levels of programming. Political choices determine what can be pursued, while economic strategies indicate the limits of each intervention; last but not least is the notion of environmental sustainability in its broadest meaning that encompasses issues of energy, economics, function, technology and, above all, society. We will attempt to further narrow the field by considering the rehabilitation of a complex industrial district: the first methodological choice concerns the type of analysis (the reading) adopted to acquire notions useful to the development of a concept design. Architectural debate, in particular in Italy, was witness to the articulated development of diverse positions. A rich selection produced a number of fixed points that will be synthetically referred to. We shall expose the case of Porto Marghera, the Venice industrial district: readings and studies developed within our university research unit and with the help of research-fellows, degree students, phd students.