That the castle at Cesky Krumlov, in the Czech Rep, has a real, populated BEAR moat. Apparently BEARS were commonly kept in castle moats as a first line of defence in parts of Europe with BEAR populations during the 16th and 17th centuries. Unlike human soldiers, they don't need to be paid or want holidays or fall asleep at inconvenient times like a cold winter's day. Oh, maybe not that last part.
Disappointingly, the current BEAR population of Cesky Krumlov's BEAR moat is one (1) bear.