The church is not treated as an empty shell waiting for a fit-out. A second, reversible ground and a family of autonomous columns introduce everything the festival needs without pretending to be old. Concept ERMA TENE adapts the Church of SS. Marcellino e Pietro for the Monteverdi Festival through a small number of dry, reversible interventions. Survey, acoustic study and diagnosis establish the limits of the project; traces of time stay visible. Photogrammetric and geometric surveys record the nave, vaults and roof structure. Cracks, moisture, surface decay and construction discontinuities are read as evidence rather than imperfections to erase. Structural, hygrothermal and acoustic analysis links each conservation choice to the actual behaviour of the building. Repairs remain local, compatible and proportionate, preserving the legibility of time while making continued use possible. System A floating technical floor protects the historic pavement and changes configuration for concerts, exhibitions and rehearsals. Slender opaline-glass columns contain light, air, sound and safety equipment, keeping every new service independent from the church fabric. The floor is a dry construction laid above the historic surface. It distributes new loads, conceals inspectable services and can remain level, rise into a stepped auditorium or create local platforms for performers and installations. Adaptability happens inside the new system, without repeated alteration of the church. The columns gather functions that would otherwise be scattered across walls and decoration. Their inspectable steel frames contain lighting, extraction, sound reinforcement, emergency information and fire-safety equipment. Ventilation and radiant systems run below the floor and return air through the columns. Calibrated to the rhythm and proportions of the nave, these elements remain clearly contemporary without competing with the existing architecture. The entrance completes the intervention as an accessible public threshold within the cultural geography of the festival. Credits Project team: Cristian Casiraghi, Federico Martorana, Anita Rizzi, Arturo delli Ponti, Chiara Tabladini. Professors: Angelo Giuseppe Landi, Annalisa Galante. Politecnico di Milano, Laboratory of Design for the Conservation of Built Heritage, A.A. 2025/2026.