She has met 12 U.S. presidents, from Herbert Hoover (after he left office) to Barack Obama, more than a quarter of all the U.S. presidents since Independence. She is due to host President Donald Trump for a state visit later this year.

In photo: Queen Elizabeth II is flanked by former President Herbert Hoover, left, and New York City's Mayor Robert Wagner at luncheon in the hotel Waldorf-Astoria, New York on Oct. 21, 1957. (AP Photo)