In a society that recognizes the urgency of safeguarding the environment and drastically limiting land transformations and energy-intensive activities like constructing new buildings, the protection of architectural and environmental heritage is no longer merely a cultural and identity-related need for communities. It has now become an essential endeavor for the survival of all living beings. This realization only strengthens the concepts of preservation, conservation, responsible use, and sustainable transformation. Simultaneously, institutions and civil society must collaborate to empower actors and tools for conserving and responsibly using built heritage. Historical architectural archives play a fundamental role in this regard. Architectural archives can be housed by various institutions such as state or local authorities, museums, libraries, public or private foundations, as well as universities and technical schools. The nature and cultural orientation of the hosting institution influence the mission, organization, management, and potential growth of the historical architectural archive. This means that the responsibility for selecting what deserves preservation in architectural archives, thus passing it on to history and the reasons behind it, lies with the archives. And the choices made by the archives should align with the mission, objectives, and cultural policy of the parent institution that houses them. Taking the case of the Archives de la construction moderne at the Ecole polytechnique fédérale de Lausanne in Switzerland as a reference, the introductory part of this article will define the unique nature of an architectural archive embedded within an academic institution. It will describe the advantages and peculiarities of such a condition and illustrate possible missions and activities that enable the fulfillment of these missions. The subsequent development will be divided into two main parts. The first part will explore activities that contribute to the preservation of built heritage, which can be divided into two groups: 1) activities directly involved in safeguarding or appropriately transforming a building (such as detailed historical and technical analysis to support design choices during restoration or transformation projects), and 2) activities contributing to academic education and the generation of new knowledge in architectural history, architectural theories, construction culture, and heritage conservation. These latter activities are fundamental to historical architectural archives. These archives not only preserve documents and drawings related to constructed buildings (as is the case with archives hosted in public building departments, for example) but also numerous documents that testify to unrealized projects, research in theoretical and applied fields, correspondence, and photographs capable of describing the formation and transformations of professional relationships, and sometimes even friendships, among architects, engineers, theorists, historians, officials, etc. The archive goes beyond mere document preservation; it represents an organized system of interconnected information within a broader network, both internal and external to the archive itself. Researchers elaborate on and contextualize these interactions, enabling a complex portrayal of architectural and construction culture. The second part of the text will address the archive as a heritage object that requires attention, conservation, and, where applicable, growth. This section will discuss the main theoretical, technological, and social changes that currently have a significant impact on the preservation and conservation function of archival heritage. These changes include the use of advanced information systems, the remarkable expansion of multimedia and native digital documents, the proliferation of complex document aggregations, and the increasing need to promote access and dissemination of preserved archives. The new ways of perceiving and using architectural archives present challenges, both technical and methodological, in properly preserving the integrity of fragile media and managing information authenticity. The tension between preservation and the need for digital access and dissemination will be examined, acknowledging the importance of striking a balance between these demands. It will highlight the need for careful considerations and appropriate strategies to ensure the long-term conservation of the archive while embracing the opportunities that digital technologies offer for wider accessibility and education.