Astaldi’s most recent experiences in the field of designing and building underground metros, both in Italy and abroad, have demonstrated the possibility of implementing technologies traditionally used in other industrial fields, such as mass production and assembly lines. This evolution becomes a must when public opinion expects very short times for producing an infrastructure that the population strongly demands. The “Monumentale” station on the new Line 5 of the Milan underground is an example of application of a prefabrication technique for building a traditional cut & cover structure in a very short time, and in a highly complex situation logistically. The article shows this process starting from the concept to design and realization.