Princess Elizabeth Alexandra Mary was born on April 21, 1926 in London to the Duke and Duchess of York, and was their first child. As the first born daughter of the ruling monarch, King George VI, she was destined to become Queen Elizabeth II. Throughout her life, Queen Elizabeth II has dedicated herself to public service and has reigned as Queen of the United Kingdom and other Commonwealth realms for over 70 years, making her the longest-reigning British monarch in history.