The fortress, called Schwanstein (it is my understanding that this translates literally to "swan rock," but really means something more akin to "Land of the Swan") was used by the Knights of Schwangau from the 12th into the 16th centuries. Legends abound about the Knights of Schwangau being the knights of the Arthurian Holy Grail. In fact, Lohengrin was supposedly the son of Percival, the Knight of the Round Table who proved to be pure enough to find the Grail, only to have it slip from his grasp due to lack of seasoned wisdom (the legend varies from here, it seems, in some with the Grail never found, in others Percival is one of 3 knights to finally take posession of the Grail). Anyway, the legends surrounding the Knights of Schwangau assume that the Grail was indeed found and gave mystical powers to the knights to do all sorts of wonderfully good deeds as long as they could keep their identities secret. Those powers were lost if anyone found out who did the kind deed.