To be inscribed on the UNESCO World Heritage List, properties must be of Outstanding Universal Value and meet at least one of ten criteria as explained in the Operational Guidelines for the Implementation of the World Heritage Convention.
The nomination of Porticoes of Bologna is based on criteria II and IV:
Criterion II:
Exhibit an important interchange of human values, over a span of time or within a cultural area of the world, on developments in architecture or technology, monumental arts, town.planning or landscape design.
The portico, private space for public use, place of excellence for social life, relationships and exchanges, finds in Bologna, an exceptionally complete and representative expression of all urban functions, in the set of selected components.
A multicultural, international and multi-ethnic place of expression, encounter and confrontation, Bologna, with its porticoes, has represented, also for the role of the University in the dissemination of knowledge, a propelling center of models widespread at international level.
In particular, this continuous and constant exchange has allowed the diffusion and the continuous re-proposal of the architectural porticoed model all over the world. Numerous architects, painters, sculptors and artists in general arrived in Bologna, for study or pleasure, worked on the porticoes and lived in them, breathing in the liveliness and activism characteristic of the city porticoes, and brought this element elsewhere in Italy and in the world, in every historical period.
Criterion IV:
Be an outstanding example of a type of building, architectural or technological ensemble or landscape which illustrates (a) significant stage(s) in human history.
The series of Bologna’s porticoes, selected in the context of the porticoed system that permeates both the old historical city and the contemporary one, represents in an exemplary manner an architectural typology of ancient origin and wide diffusion, never abandoned until today, but in continuous change through precise historical periods of the town’s transformation.
The series exemplarily represents, in the various chronological, typological, technological and functional declinations, a variety of porticoed building typologies, widespread among the houses of the working class and the aristocratic residences, the public and religious buildings, which were developed in the centuries from the 12th to the contemporary era, with a wide range of materials and styles, as a result of the city that expands and changes over time.