Which is confusing because the actual design of the castle is from the movie Sleeping Beauty. :-P
It’s original intent was in fact to be a room For Walt and his family. After Walt died in 1966, the apartment was left unfinished.
Response to 10 Disney Films You Totally Forgot About:
I loved The Black Cauldron BECAUSE it was dark. Also I was surprised when I went to Tokyo Disneyland and they had a ride inside the castle based on that film.