His castle has no door and no window. Even no wall or human construction at all. It simply disappeared because it has been set one fire one day for some reason and came back to normal after a few years, nowdays it is quite peaceful and full of vegetation. It is possible to eat most of the plants there. Eating plants provides a huge amount of entertainment. If you feel too much entertained, he will first allow you to ask for one wish. I have to warn you : it has to be a passive wish.