Born Margrethe Alexandrine Porhildur Ingrid, this member of the Danish House of Glücksburg was crowned Queen of Denmark at the age of thirty-one.
At thirteen years old, she became first in line to her father's throne after an amendment was passed that granted eldest female children of regents the right to rule.
She took archaeology courses at Girton College, Cambridge, and later studied at the Sorbonne, Aarhus University, and the London School of Economics.
She was born at Copenhagen's Amalienborg Palace to Ingrid of Sweden and King Frederik IX. Her marriage to Henri de Laborde de Monpezat resulted in sons named Prince Frederik and Prince Joachim.
She and Elizabeth II became two of the longest-reigning queens in history.