king of the castle vs observation wheel

king of the castle

noun
  • A children's game in which one player is located on something elevated and other players attempt to take his or her place. 

  • An individual who assumes a position of greater importance, authority, or prominence than others. 

observation wheel

noun
  • Ferris wheel 

How often have the words king of the castle and observation wheel occurred in a corpus of books? (source: Google Ngram Viewer )