According to legend in the late 16th and early 17th centuries there lived a very beautiful, and very vain countess of Hungary from which Bram Stoker got a lot of his ideas. Erzsébet Báthory of Hungary supposedly bathed in the blood of young virgins (in some legends even drinking it), so that she would not grow old and would remain young and fair indefinitely. When the authorities finally accused her of witchcraft, satanism, and the aforementioned weird blood rituals, she was sentenced to life in her walled up torture chamber (for political reasons they couldn't kill her), without trial. Only a small opening allowed her jailers to feed her. Whether or not any of the charges were true she is still known to the Slavs as The Bloody Lady of Cachtice Castle, or The Hungarian Whore.
You're correct about the story and it's NOT a legend. The woman was actually close family to king Stephen Batory of Poland and Siebenburgen...