2014: Pardon my ignorance, but I don't know if there is any difference between castles and palaces. I'm sure I've been to several palaces already in the many countries I've visited. But castles sound so medieval, like something you'd find in fairy tales, with moats and drawbridges. If so, then this one in Luxembourg would be the first-ever that I've visited.
2012: And this is a Disney one in Universal Studios Singapore. :-)