For this reason, between the XI century, because of the great economic development of the cities and the population increase, the municipal authorities needed to put their cities in order: further invasion of public space was prohibited and some bulky buildings - or part of them - were demolished.
Up to that moment, the history of Bologna was the same as the one of other cities.
But the history of its porticoes was destined to change.
At the end of the XII century an important change took place: actually it was no more possible to build porticoes (people needed be licensed to use public space).On the contrary, in Bologna porticoes were defined as compulsory for all the streets where they were considered useful on In 1363, it was ordered that no wooden porticoes should be built any longer, and in 1567 it was ordered that wooden pillars should be replaced by brick or stone pillars.Nevertheless, there are still extant nowadays some wooden porticoes dating back to the 13th century. Derfor har vi samlet Danmarks dejligste senior singler der er klar til at nyde livet med en ny partner. Livet er mere vidunderligt når man kan dele det med nogen.
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Thanks to their great diffusion and permanence, the Porticoes of Bologna are considered as 'outstanding universal value'.
Their long permanence and use (about 1,000 years) are due to the importance given to these artefacts in the city of Bologna through the centuries.
In the Middle Ages all the developed cities were characterised by porticoes.
Generally, this phenomenon is due to the need of space for dwellings and occupation during a period of economic development and, at the same time, to poor control of public space by the authorities.