On this day 90 years ago (23 February 1934) Prince Leopold, the Duke of Brabant, became King Leopold III, the 4th King of the Belgians, 6 days after his father's sudden death.
A depiction of his swearing-in ceremony in a tapestry from 1947:
On this day, 65 years ago (12 April 1959), the engagement announcement of Prince Albert, Prince of Liège to Donna Paola Ruffo di Calabria.
A pic from that day, taken by King Baudouin (it was shared by the Royal Palace in 2019, for their 60th wedding anniversary):
On this day, July 25, 1876 ~ Birth of Elisabeth of Bavaria, Queen Consort of King Albert I of the Belgians at Possenhofen Castle in the Kingdom of Bavaria
On this day, August 23, 1836 ~ Birth of Queen Marie Henriette of the Belgians, wife of King Leopold II of the Belgians, born Archduchess Marie Henriette of Austria at Buda Castle in Budapest, Hungary
On this day, September 19, 1902 ~ Demise of Queen Marie Henriette of Belgium (Archduchess Marie Henriette of Austria), wife of King Leopold II of Belgium, at the Hotel du Midi in Spa, Belgium