Il tracciato delle fortificazioni tra valenze ideative e processi trasformativi: le mura Aureliane e il Mattatoio di Piazza del Popolo a Roma nel XIX secolo

The layout of ancient walls has always played an important role in the development of cities, both at the time of their construction and in subsequent centuries, defining the evolution of the morphology of the urban structure, the shape and articulation of new buildings falling within the area of the defensive system. In the case of Rome, the Aurelian walls, whose construction was started during 270 A.D., to extend the Servian walls, present over the centuries new defensive elements and inclusions in plots dedicated to activities for the city of civil type, residential, and religious.In the nineteenth century, the area of Porta del Popolo underwent several transformations. Still, in particular, the part facing the river Tiber, occupied by the public wood, is transformed for the expansion of the slaughterhouse of Rome and the adjoining livestock market, located in suburban territory. From 1823 to 1888, the year of construction of the new slaughterhouse in Testaccio, the layout of the walls led to the consideration of new layouts and solutions between the parts of the slaughter complex, acting as both an obstacle to direct usability between the parties, and as a creative value in terms of modules, measures, and types of buildings. It shows, as well, how castles, towers and fortresses can abandon their original role and become ideative valences within the processes of transformation of the city.