The Po, Italy's longest river, starts near the French border, high in the Alps, and cuts across the country to empty into the Adriatic just south of Venice.
From start to finish, the Po River travels more than 400 miles across northern Italy, winding its way through Turin, Piacenza, and Ferrara. It's the Po that Milan's canals were built to connect with. This river has historically been important for thousands of years – even in the second century B.C.E. scholars were puzzled over its name, indicating it had been named long before that – and the Po Valley remains one of Italy's most fertile areas.
One of the main agricultural crops grown in the Po Valley is rice, thanks to the river's abundant flow, but that abundance also means frequent flooding. Dams and dykes help keep damage in cities to a minimum now, but the plains are still at risk for flood damage.
The Po Delta, where the river begins to split apart on its way to the sea, is now protected as an inter-regional park in the Veneto and Emilia-Romagna regions. The latter has the larger portion of the delta, and there are several visitor centers and museums in the park grounds. You can explore the area on your own or go on a guided nature tour.