Nienburg is first mentioned in travel records dating from 961. The medieval centre of the town is occupied by the Benedictinemonastery, Nienburg Abbey, later turned into a castle, recently destroyed by fire. The church of the monastery, over 1000 years old, was inaugurated in 1004, and is beautifully preserved to this day.
In 1623, during the Thirty Years' War, part of the town was destroyed. In 1825 an early suspension bridge over the river Saale was constructed, but because of unforeseen vibrations it collapsed during the inauguration festivities, resulting in over a hundred casualties.