Portici represent, along with the many towers, the symbol of the city of Bologna. All together, they measured in length over 38 kilometers just in the center. Candidates "World Heritage" by UNESCO, the arcades were born in the late Middle Ages because of the increase in population due to the presence of the University: the need to increase the living spaces, it led at first to increase the cubic houses expanding the upper floors with extensions supported by beams externally beams, first, and then the pillars, often ruled by "beccatelli". In the second half of the sixteenth century, were built some of the most important-loggia arcades of Bologna. The Portico of San Luca is the the world's longest: measuring 3.796 meters and consists of 666 arches, starting from Saragoza Gate, leading to the summit of the Colle della Guardia, where stands the famous Sanctuary of the Madonna di San Luca. The Portico of the Basilica of Santa Maria dei Servi is, however, the wider: originally designed by Antonio Di Vincenzo, its construction began in 1393.