Grand Duke's Official Birthday is the national day of Luxembourg.
It is celebrated on June 23 each year regardless of the actual birth date of the current Grand Duke.
The Grand DuKe of Luxembourg is the monarch of Luxembourg.
The first Duke of Luxembourg was William I, his actual birthday was August 24, but the official birthday was celebrated on April 24.
His successor William II was the first monarch of Luxembourg whose actual and official birthdays were celebrated on the same day, it was December 6.
The sovereign's birthday was declared the national day of Luxembourg in 1947.
As then-reigning Grand Duchess Charlotte was born in January, the celebration was often spoiled by bad weather.
In 1962, the date was fixed on June 23.
If June 23 falls on a Sunday, the celebration is moved to June 24.