The Aller is a river, 211 kilometres (131 mi) long, in the states of Saxony-Anhalt and Lower Saxony in Germany. It is a right-hand, and hence eastern, tributary of the River Weser and is also its largest tributary. Its last 117 kilometres (73 mi) form the Lower Aller federal waterway (Bundeswasserstraße). The Aller was extensively straightened, widened and, in places, dyked, during the 1960s to provide flood control of the river. In a 20 kilometres (12 mi) long section near Gifhorn the river meanders in its natural river bed.
Read more about Aller: Aller Glacial Valley, Castles and Monasteries, Culture and Tourism, Hydrology, Water Power