https://de.wikipedia.org/wiki/Habsburg_(Burg)

> Da er zu wenig Geld für den Bau der Burg hatte, bat Radbot seinen Bruder, Bischof Werner von Strassburg, um Unterstützung

> Because of insufficient funds to construct the castle, Radbot begged his brother, Bischop Werner of Strassburg for support.

Whether or not that's a legend, it was not unbelievable, which is the whole point.

That castle was situated at an impasse of a river, where they likely extorted money, I mean "took taxes". The rest is convoluted history. I guess you heard the name.