It has rightly been claimed that the picture inhabitants have of their city is, in fact, an imaginary perceptual image shaped by the learning processes of a specific social environment. That applies in particular to public space, where expectations are dominated by the piazzas and squares one knows from Italy and Spain. Even if public space is high on the political agenda, it remains for the most part strangely ill-defined. Many prophecies have been made that in the future, man will spend his time largely in front of computer or other screens in a realm of virtual reality, travelling on information highways and in cyberspace. Despite the widespread use of modern mass media, these are not in a position to replace the spatially perceptible public realm. Similarly, although a lot of formal social occasions may take place in private, indoor spaces, there are still many public events that are held outdoors: addresses, concerts, festivities, demonstrations, processions and the like; and external spaces in historical cities provide an ideal stage for the articulation of social conflicts.