When we imagine the "Teatro alla Scala", the pictures that are brought to mind are those of its monumental front, of its lounges and of its magnificent internal hall. A lot less is known however about its interior, that is, what lies behind the Boccascena (the proscenium), where the scenic machine, the auxiliary systems and the laboratories which form this complex theatrical mechanism, are to be found. At 2001 the historical-monumental part and the hall of the Theatre clearly needed restoration interventions, while the backstage, subjected to the wear of time, having gone through haphazard additions and continual adaptation over the years, was no longer able to meet the requests of a today's theatre. The project of the New Teatro alla Scala was hence composed by two distinct parts: the project of the refurbishment and of the restoration of the historical-monumental part (the past) and the project of the buildings for the new scenic plants (the future). These two different views of the theatre have therefore been reflected in the two different objectives given to the project: its first aim was to safeguard the theatre's historical value and to maintain its right to remain an icon of Milan; the second was to create new structures and spaces in order to supply a solid platform to support a theatrical mechanism worthy of the Teatro alla Scala. The refurbishing works had to face a number of difficult issues, most of them caused by the theatre location in the centre of the town, by the small space at disposal, and, eventually, by the absolute absence of an erecting yard area. Demolition and construction works have been preceded by an attentive scheduling, which has simplified the phases of realization and allowed to meet the contract dead-lines. Criteria and the techniques followed to plan the demolition phases and the main aspects concerning the design and the construction of the buildings of the new scenic plant are presented.