In La Tavola Ritonda, a castle visited by Galahad, Perceval, Bors, and Perceval’s sister Agresizia (Agrestizia) during the Grail Quest.
It’s lady, Verdoana, suffered from a leprosy which could only be cured by the blood of a virgin. All passing ladies were therefore asked to provide a sample of their blood.
The three knights fought to protect Agresizia, but she eventually consented and perished during the bleeding. Verdoana, however, was cured. This episode appears in the Vulgate Queste del Saint Graal and its other adaptations, but the castle is unnamed.
Lepreous Lady, Castle of the | The Legend of King Arthur