Denmark's Princess Mary didn't realize her now-husband Prince Frederik was royal when they met at a pub

• Australian-born Mary Donaldson didn't know Prince Frederik was a prince when they met in Sydney.
• Mary, who is now formally known as Princess Mary, married Frederik in 2004.

Crown Prince Frederick of Denmark and Princess Mary have been married for 19 years.

The future king and queen are full-time working royals and are often photographed out in public in Denmark's capital city, Copenhagen. Most recently, they were pictured welcoming the King and Queen of Spain to the city last week.

But their relationship wasn't always so public. The princess was born Mary Donaldson in Tasmania, Australia, in 1972 and was working as a real-estate agent when she met Frederik in 2000, according to the couple's 2003 interview with Tara Brown for "60 Minutes Australia."

Mary didn't know Frederik was a prince when they met at a pub in Sydney

The couple first met at the Slip Inn, a pub in Sydney, Australia, according to the Mail Online's Jessica Green and Daily Mail Australia's Alice Murphy. Frederik was visiting the country to watch Denmark's sailing team in the Olympics, the report added.

"The first time we met or shook hands, I did not know he was the Crown Prince of Denmark," Mary told "60 Minutes Australia."

"It was perhaps half an hour or so later that someone came up to me and said, 'Do you know who these people are?'" she said.

Shortly after meeting, the couple began dating long-distance, which Mary said was beneficial in establishing a deep connection.

"Everything was through words, so it established a really strong relationship to begin with," she added.

As a founding member of the Commonwealth, an international organization that's made up of many of Britain's former colonies, Australia recognizes Britain's monarch as its head of state.

Growing up in Australia, Mary had an awareness of British royalty, but she wasn't an avid royal watcher since there wasn't "a great deal of presence unless there was an official visit," she said in an interview with the Financial Times' Anders Christian Madsen in 2022.

However, her position has changed in the years following her wedding to Frederik at Copenhagen Cathedral on May 14, 2004.

Speaking to Madsen, Mary said she has an admiration for Britain's late Queen Elizabeth II and her mother-in-law, Denmark's Queen Margrethe II, "for their lifelong commitment and dedication to serving their country and their people."

Today, Mary and Frederick work to support Margrethe at official events with their royal patronages. In 2007, the princess created The Mary Foundation, which aims to prevent social isolation by tackling three areas: "Bullying and well-being, domestic violence, and loneliness," according to Mary's biography on the Danish royal website.

Meanwhile, the crown prince supports more than 35 organizations that have a focus on "business, culture, sports, sustainability and social purpose," according to his biography on the Danish royal website.

The couple's first child, Prince Christian, was born in 2005. Their second child, Princess Isabella, was born in 2007, and they welcomed twins Prince Vincent and Princess Josephine in 2011.