Conversation so far:
What was the occupation of Sicily for Richard I of England?
In September 1190 Richard I of England and Philip arrived in Sicily demanding that his sister, King William II of Sicily's widow, Queen Joan, be released and given her inheritance.
How much was Queen Joan's inheritance from King William II of Sicily?

Question: where was his sister imprisoned?
Self-contained rewrite: Where was Richard I of England's sister Queen Joan, widow of King William II of Sicily, imprisoned?