An intervention carried out in a pre-existing building designed by J. Cruz Lima dating back to 1950, built under a private promotion regime. An extensive period of absolute inactivity and abandonment sped up the degradation process of its structure, with frail construction features. Within this context, the intervention on the building was geared towards maintaining the aspects that had made it a reference in Santo Tirso: its image and function. The project must assure the integration of additional conditioning factors, options sustainability and compliance with current regulations and laws. Its concept is grounded on the design of a building within a building; a new container within the pre-existing shell. The conceptual principle is at the core of the intervention and articulates, in one single gesture, the architectural and structural premises, with those of a programmatic and strategic nature. The idea of a scenic container – that is structurally independent from the pre-existing building – capable of accommodating various performing arts, the “stage” for various models of scenic and recreational use, also includes an entire infrastructure and supporting technology, suitable with regulatory frames and the new formats of the performing arts. From an architectural point of view, this concept fits the preservation of the structural and linguistic integrity of the existing building by ensuring, in a qualified manner, its construction rehabilitation, architectural language, presence, and urban scale.