Nienburg Museum is the town's main local history museum, with the Fresenhof as its most attractive building. The half-timbered former Burgmannshof has roots in the medieval town and took much of its present form in the early modern period.
The collection focuses on the Mittelweser region rather than trying to tell all of German history. That local focus is the point: it helps explain the river town, its trade, and the rural country around it.