Ultra-high-resolution gigapixel images, three-dimensional reliefs, virtual tours, and a digital archive will help document and preserve the Basilica of Saint Francis in Assisi across time. This is "Preserving Assisi", a new digital portal dedicated to the basilica complex, launched in honor of Saint Francis' eighth anniversary. The project's goal is to create increasingly thorough documentation of the Basilica and its creative history over time, thereby facilitating knowledge, research, monitoring, and conservation. The program also lays the groundwork for a gradually evolving digital twin of the basilica complex, a digital record of its architecture, paintings, surfaces, and state of preservation. The National Committee for the Celebration of the Eighth Centenary of Saint Francis of Assisi's Death, the Umbria Region, and the City of Assisi have funded and supported the initiative, which is being created in conjunction with the University of Florence. "Preserving Assisi" is built around an integrated system of technology for digitization, management, and data access. The projects combine ultra-high-resolution gigapixel photography with three-dimensional surveys of the Basilica's interior and external spaces, as well as its decorative embellishments. The acquisitions enable detailed documenting of the monument's form, color schemes, surface features, and condition of conservation.