River, central Italy. It is 150 mi (240 km) long, flowing west from the
Apennines through
Florence and into the Ligurian Sea below
Pisa. Near Arezzo it is connected with the
Tiber River by its canalized tributary, the Chiani. Subject to disastrous floods, in 1966 it inundated Florence and caused extensive damage.
For more information on Arno River, visit Britannica.com.