The intervention on the Castellana 44 building focuses on intensifying the presence of its powerful structure, transforming the expression and thermal behaviour of its façade and improving the performance of its spaces. Its powerful roof structure, now hidden among air conditioning installations, is incorporated into the interior space of the penthouse floor. Its heavy and heterogeneous façade is transformed into a light folded veil that builds a simple and effective “active” thermal cushion. The reconfiguration of the accesses and circulations allows for an intensive, flexible and efficient use of the building.