The castle was founded over the Weibe Valley together with a settlement by the Counts of Nassau as a corner post of their domain. Count Johann IV of Nassau, Vianden and Diez gave the Freudenberg townsfolk their "freedom rights" on 7 November 1456. This was a kind of minimal town rights, but the document bestowing this distinction upon the town is taken as evidence of town rights being granted Freudenberg. Documents give clues that Freudenberg was established quite early on as a ""Flecken"", or market town. The historic town core is even still called "Alter Flecken" ("alt" means "old"; "–er" is a grammatical inflection).