This work concerns the seismic isolation of one of the masterpieces of Renaissance sculpture in Umbria: the ciborium of the main altar in the Church of Santa Maria Maggiore in Spello, Italy. The intervention strategy was defined following a critical evaluation of the base isolation solution, supported by experimental tests aimed at the dynamic characterization of the sculpture.

An in-depth understanding of the original construction techniques, materials, structural details, and their state of conservation was, of course, of considerable importance. The studies and analyses carried out indicated that seismic isolation is likely the only viable solution capable of drastically reducing seismic risk without resorting to invasive interventions. In fact, by focusing the intervention primarily at the foundation level—beneath the monument itself—the sculpture remained unaffected by significant alterations.

The execution of the work presented considerable challenges and was conducted with “zero tolerance” for any movement or deformation of the sculptural group. Careful planning of each construction phase, combined with the technical skill of the executing company, ensured the desired outcome: throughout all phases, no movement or deformation occurred in the ciborium or the altar. Both elements were kept in place during the excavation and construction of the isolation layer, with dismantling limited only to the flooring.