In Bologna the arcades, a singular element in other cities, are a systematic feature. Not that they do not exist elsewhere, but here you have more than 40 km of them, and nearly any stroll in the historical core can be done through them. In many cities, they are an element complementing the sidewalk, but here they substitute it almost completely. This implies that sometimes a pedestrian does not see clearly the vehicles until he decides to do it (not necessarily a good thing), but also that anyone stopping a car must be more attentive. During winter, if ice appears, sunrays do not touch the pedestrian area, so there is a risk of slipping, but if there is just rain you are covered. Compared to other historical cities there are very few sidewalks, and even pedestrian streets, but when you walk you feel much more protected; even if they wished to do so, cars and trucks could not occupy the pedestrian space but through unusual means.
It seems the arcades appeared during the XIIth century, when streets were wider, as a solution to extend buildings to cope with a surge in the university population. In 1288 a municipal ordinance made brick or stone arcades mandatory for any building, even if today some wooden arcades remain. The key measure were 7 Bologna ft in height (2,66 m), enough to allow the passage of a man astride his horse. In law terms, it was a compulsory easement by which the public use of the arcade was guaranteed and it was to be kept in good use by the building owner, in exchange for the right to use the spaces in the floors above. As a compulsory architectural element in any building, it has taken varied shapes, in palaces and in humble homes, with a large diversity.
The Bologna arcades (Portici Bolognesi) are candidates to enter the UNESCO world heritage list.
These arcades have also probably survived due to another factor: compared with other historical cities penalised by a position atop a hill, Bologna’s historical core and its surrounds are almost flat, so pedestrians have it easy.