A boundary wall erected by the Republic of Venice as military defense around the city of Treviso the early 1500s and represents a vital urban reality. The walls are formed by a raised embankment a few meters, supported outside by a thick wall of bricks and encircled by water and green areas, around which a ring road that circles the roads that connect from all directions arrive in the city. On the north side embankment is still almost fully preserved: full of trees and greenery, is a quiet stroll and where, so you can appreciate the appearance of the city and immediate suburbs. But in ancient chronicles and descriptions of the city, these buildings will be exalted above all the defensive role. An anonymous end of'500 writes that if the city walls were in better shape than at, the city would be "... one of the best fortresses that are all over the world."
An interesting observation point is the Ponte Fra 'Giocondo (formerly Ponte de Pria, developed in 1521), a massive construction of seven arches under which the city reached one of its major rivers, the Cagnan. The other is the Sile, Treviso river crossing in the south, from east to west, from resurgences of Casacorba (Vedelago). The meeting of these rivers has given rise in the past to islets of gravel and clay grown to form small hills. The highest of these excavations have made it possible to date the oldest settlements to the Bronze Age average (XVI. BC).
The village has expanded in stages, and each time the acquisition of new land is extended until the next river, which at different stages of urban rivers and channels have always been the natural limit and the first line defense of the city. In this way the Cagnan and Sile have traced the perimeter of urban Tarvisium Roman, then the medieval Trivigi of Treviso and Venice.
The Cagnan is the walls of Treviso with the name of Botteniga making way between the trees of the gardens and promenades. E 'consists of dall'apporto resurgences of Fontanelle and Pegorire, which has added the channel Piavesella resulting from Piave for a work irrigated. Not all the water enters the Botteniga in passing beneath the city walls, but part of the laps constituting the External Fosse, with appropriate hydraulic dams could lead to an unworkable band acquitrinosa thereby strengthening the defense system. Today the first section of western ditch is covered, creating gardens and Pattinodromo (Viale Fratelli Cairoli).
Within the walls Botteniga, now Cagnan, branches off in three directions across the city to bring in Sile in separate mouths. To the west branch in the first section is called and then Siletto Roggia, and at the center Cagnan de Mezo (also known as the Buranelli, or the Hospital of Beccherie depending on the zone cross); Cagnan to the East or the Big Fish. The city has always intensely exploited these waters and their energy. Suffice it to say that in 1685 were surveyed and described along the canals of Treviso seventeen "posed" by mills moved from thirty-six wheels, owned by prominent families and monasteries.
The waters of Cagnan come together in the national fabric, lap and enter the houses, accompanying streets of pebbles and arcades chiaroscuro, creating reflections of light and glimpses of unpredictable charm.