The earliest official mention of Nienburg/Weser dates from the year 1025, when Milo, the Canon of Minden, apparently made a gift of his property in Nienburg to the Minden church. Since this early mention spoke of Nienburg (= new castle), some kind sort of fortress must already have existed there for some time, perhaps in order to protect the crossing of the Weser. Under the protection of this fortress the initially insecure settlement became permanent, and was first officially referred to a "civitas" (a town) in 1215.