Crown Princess Mary and Crown Prince Frederik of Denmark stepped out in regal finery for the 50th birthday of Fred's little brother, Prince Joachim on Saturday night.
Queen Margrethe II hosted a lavish gala dinner at Copenhagen's Amalienborg Palace for her youngest son's milestone celebration, which was the first time her eight grandchildren attended an official state banquet.
Australian-born Princess Mary, 47, looked elegant in an asymmetric duck egg blue ball gown and delicate silver clutch, while 51-year-old Prince Fred was dapper in a midnight blue evening suit.
WATCH this video to see the VERY different activity Mary and Fred got up to the next morning!
The Crown Prince couple's four children, Prince Christian, 13, Princess Isabella, 12 and eight-year-old twins Prince Vincent and Princess Josephine beamed as they posed for family photos outside the Palace.
Queen Margrethe, 79, dazzled in a blue and white floral maxi dress as she welcomed her sons and their families with open arms.
Dressed in a white dinner tuxedo, Prince Joachim brought his four children, Prince Nikolai, 19, Prince Felix, 16, Prince Henrik, 10 and seven-year-old Princess Athena and his wife Princess Marie to the special event.
Prince Joachim's ex wife, Countess Alexandra, also attended the banquet along with the French Ambassador to Denmark, Francois Zimeray and other members of the Danish royal family, Daily Mail reports.
Crown Princess Mary and Prince Fred shared stunning shots from the party on the Danish royal family's official Instagram account, Det Danske Kongehus.
But despite their weekend of socialising, Princess Mary and Prince Fred proved they are committed to maintaining a healthy lifestyle by taking their four kids out for the 2019 Royal Run in Aalborg on Monday morning.
Last year, it was just His Royal Highness Prince Frederik who donned running shoes to join the 70,000 Danes taking part in the event which spans the country's four largest cities: Aarhus, Aalborg, Copenhagen and Frederiksberg.
Mary and Fred first crossed paths at Sydney pub The Slip Inn during the 2000 Olympics.
Then just 28, Mary Donaldson had no idea she was chatting to the Crown Prince of Denmark - but just four years later on May 14, 2004, the royal couple married in a fairytale wedding at Copenhagen Cathedral.
As they say, the rest is history!