There are 5 canals in the Navigli lombardi system: Bereguardo, Grande, Martesana, Paderno and Pavese. These are the oldest artificial canals in Europe. Built from the 12th century onwards, they made it possible to link Milan with Lake Maggiore (by means of the River Ticino), Lake Como (through the River Adda) and the city of Pavia and River Po. They were major waterways for the purposes of transport and irrigation of the fields. A valuable heritage developed along these canals over the centuries with the summer residences of the nobility, mills, castles, abbeys, and rural and natural landscapes of exceptional beauty.