Alzenau is a town in the north of the Aschaffenburg district in the Regierungsbezirk of Lower Franconia (Unterfranken) in Bavaria, Germany. Until 1 July 1972, Alzenau was the district seat of the now abolished district of the same name and has a population of around 19,000.

Lower Franconia is one of seven districts of Bavaria, Germany. The districts of Lower, Middle and Upper Franconia make up the region of Franconia. It consists of nine districts and 308 municipalities.