The Prince of Wales will fly to the Middle East today for a short tour.
Charles's four-day trip to Saudi Arabia and Qatar comes just under a year since he last toured the two nations.
The heir to the throne's tour has a large majority of private engagements.
But highlights of his public events include a tour of an old Saudi Arabian city and in the Qatari capital Doha he will visit a leading museum.
Charles will be welcomed in Riyadh by Prince Miteb bin Abdullah bin Abdulaziz al-Saud, chairman of the National Guard when he arrives in the country later today.
Sir John Jenkins, the UK's ambassador to Saudi Arabia, said: "Our two kingdoms share a long friendship, going back to the foundation of the modern Saudi state. Continuity of personal relationships, essential if we are to understand each other better, have been central to this.
"His Royal Highness' second visit to the kingdom in my time here as ambassador exemplifies our wish to engage at the most senior levels and our determination to sustain the personal touch.
"At a time of enormous turmoil and human agony in the Middle East, seen today perhaps most acutely in Syria, the Prince's advocacy of interfaith understanding and dialogue between communities is needed more than ever.
"His Majesty the King shares this deep concern. I know that he and His Royal Highness will have much to discuss about the need for reconciliation and their hopes for the region's future."
The visit to Saudi Arabia will be Charles's 10th official trip to the country since he first toured the nation in 1986.
The British Royal Family have a strong and close relationship with many Middle Eastern countries that are ruled by Arab royalty.
Nick Hopton, the UK's ambassador to Qatar, said: "I am delighted that His Royal Highness the Prince of Wales is to visit Qatar again. This is an opportunity to showcase the strong ties between the UK and Qatar, which we value greatly.
"The personal relationship between His Royal Highness and His Highness the Emir is both a symbol of this friendship between nations and important to the work we do together as the British and Qatari peoples to tackle the challenges facing us in the region and globally."
Charles has previously made four official visits to Qatar in 1986, 1997, 2007 and 2013.