Who is the longest-ruling Head of State in the history of Europe?

Explanation

Louis XIV (1638 – 1715)is known as the Sun King (French: le Roi-Soleil)and for the words "L'État, c’est moi!" because of his sovereign rule. He reinforced the power of the crown by extending the state bureaucracy and by supporting French trade. Art and science blossomed and France dominated Europe - not least because of the country's aggressive foreign policy. With 72 years on the throne he is the longest-ruling head of state in the history of Europe.