Bologna's medieval prosperity rested on water — a system of canals diverted from the rivers Reno and Savena powered the silk mills that made the city one of Europe's largest producers of silk thread in the sixteenth century. The Canale delle Moline drove most of the city's flour mills. Most of the canals were covered or filled in during the nineteenth and twentieth centuries; a few short stretches survive in the open.
The best stretches to find are along Via delle Moline and Via Capo di Lucca, where the water still flows past the backs of houses and under the streets. The view from the Finestrella di Via Piella is the most photographed glimpse, but a slow walk along Via Oberdan and around is the more rewarding way to trace what is left.