Vacation in a real castle

MSNBC has hit on what my idea of an ideal vacation destination is - renting a castle! Their article Turn back time, rent a castle on their website details ten places that you can turn back time and live the life of medieval luxury. The perfect escape for any fantasy writer or enthusiast. I would love to get the chance one day to travel to Europe and spend say a week living in a real castle to do some honest to goodness hands on research about castle life in the middle ages.