This article tries to bridge the growing gap between science and construction techniques by conceiving of the techniques employed as a single body with the project, which is to be interpreted as the science of construction. This is especially true in the case of the restoration of modern buildings, which has come to the attention of architects and architectural critics in recent years. The problems associated with the restoration of modern architecture are multi-faceted: protection and restrictions, restoration tools, uniformity of materials and results, limits of convertibility. Although protection and restrictions go together and fall under the definition of « cultural and artistic works » in Law 1989 of 1939, various kinds of pressure have come from different sectors. Thus the range of normative specifications is becoming more and more complex, even to the point of requiring the revision of several parts of the law. It is even more urgent that there be a sense of solidarity toward a fundamental acquisition. It is necessary that restoration shift from the purely restrictive regimen of the project: the system guaranteeing protection must become active. The attention of historians of architecture should be concentrated on a few fundamental points: the definition of the modern monument and its 'duration'; the technical instruments of restoration (materials and technology employed). According to the author, the concept of 'monument' is intrinsically associated with the concept of 'document', that is to say, evidence, or trace of the process as well as the final result. The project/technical parts of restoration, which all too often waver between reconstruction and repair, cannot ignore either aspect. The author's opinion can be summed up by the slogan: restoration of the modern, or the weak project, where the 'weakness' refers to both the artefact and its possible new invention. What led her toward this position is the conviction that a cognizant restoration strategy, in particular of modern buildings, needs the project more and more. At the same time, the project should also be understood as a tool for investigation. However, on the conceptual level, the cultural heritage of the twentieth century still has priority over tradition. It is precisely the absence of this 'new tradition' which could make both protection and restoration short-sighted. In restoring the modern, the determining factor lies in the project, which is a very complex operation and requires rules, since the authenticity of a work, with the programmed 'weaknesses' and 'fragility' of today's works, is in the hands of the architect who is in charge of the restoration job. Awareness of the limits involved is necessary in order not to abuse the significance of an artefact, thus damaging its preservation. If the culture of the modern is to have deep enough roots, the specificity of a restoration job should move toward the recognition of the uniqueness of the project as it stands, between the old and the new. Otherwise there is the risk — and the consciousness of it seems widespread — that the monuments of the modern will end up as chrysalises of sorts, and, once the last layer has been shed, they will fly away definitely and inexorably.