King Charles began his private visit to Romania, Buckingham Palace confirmed on Friday.
The monarch, 74, arrived in Bucharest, where he received a Guard of Honour at Cotroceni Palace, before undertaking a bilateral meeting with President Klaus Iohannis.
Later today, the President will host a reception in His Majesty's honour in Union Hall at Cotroceni Palace to mark 25 years since the King first visited the country.
Charles is likely to stay at his remote, rustic farmhouse in the small village of Viscri which he bought in 2006.
Charles's solo trip abroad comes just days before his youngest son, the Duke of Sussex, is expected to fly to London from California week to appear as a witness in the trial brought against Mirror Group Newspapers (MGN) by Prince Harry and other high-profile figures over alleged unlawful information gathering, including phone hacking.
It will mark the first time in more than 20 years that a member of the royal family has testified in court since Harry's aunt, Princess Anne.
LATEST: Crown Prince Hussein pens heartfelt message to new wife Princess Rajwa after royal wedding
The Princess Royal had to appear in court back in 2002, when she pleaded guilty to a charge under the Dangerous Dogs Act after her pet dog Dotty, an English Bull Terrier, bit two children in Windsor Great Park.
Harry was last reunited with his family at King Charles and Queen Camilla's coronation last month, but the Prince made a swift exit following the service to fly back to celebrate his eldest child Prince Archie's fourth birthday.
The British royal family and Romania
The Romanian and British royal families are believed to have a close relationship, and Margareta of Romania, now 74, reportedly spent her childhood summer holidays with Charles and his sister Princess Anne when they were younger. The then Prince of Wales also visited the family in Bucharest during an official tour in 2017 and attended King Michael I's funeral in December that year.
King Michael was the last King of Romania, reigning from July 1927 to June 1930 and again from September 1940 to his forced abdication in December 1947. After attending the wedding of his cousins, Queen Elizabeth II and Prince Philip in London, he was summoned by the ruling communists in Romania and told that the monarchy was to be abolished. He met his wife Anne of Bourbon-Parma at the royal wedding and the pair married in Athens, Greece in 1948.
After King Michael's forced abdication, the couple raised their five daughters (Crown Princess Margareta, Princess Elena, Princess Irina, Princess Sophie and Princess Marie) in Switzerland.
While Romania's royal family doesn't have an official role, Crown Princess Margareta formally assumed the role as Custodian of the Crown of Romania, following her father's death. As she and her husband Prince Radu do not have any children, Margareta's younger sister Princess Elena is her designated heir.
Make sure you never miss a royal story! Sign up to The Royal Explainer newsletter to receive your weekly dose of royal features and other exclusive content straight to your inbox.