The Crown of Spain (1516 present) is a series of titles and honors given to the reigning monarch of Spain. The Spanish Empire at its height was very powerful, in fact it was one of the most powerful empires. The Kingdom of Spain used to be the Crown of Castile, and the Crown of Aragon. Both kingdoms united when Isabella I married Ferdinand II of Aragon. Both crowns descended to their daughter Joanna of Castile. The Spanish Empire for a couple decades was united with the Hapsburg Empire. Today the king of Spain is Felipe VI. Felipe holds the main title as "King of Spain" but not as Holy Roman Emperor nor King of Gibraltar. The Kingdom was taken by the British and the current head of state of Gibraltar is Queen Elizabeth II of Great Britan and the united Kingdom and the common wealth. 