The British royal family had not confirmed who would be attending Prince Hussein and Rajwa Al Saif's nuptials, so the couple's attendance will come as a surprise to royal fans.
It's also the first major international royal event that Prince William and Kate attend. In the past, the then Countess of Wessex and Prince Edward have attended several royal weddings, such as Crown Princess Victoria of Sweden back in 2010 and Prince Albert and Princess Charlene's in Monaco in 2011.
The couple's aeroplane left Norfolk airport on Wednesday morning, arriving in Jordan in the afternoon.
Many other guests have begun to arrive in Jordan, including Queen Maxima and her daughter, Princess Catharina, and First Lady Jill Biden, who has flown in with her daughter Ashley Biden.
Other guests attending include Princess Takamado of Japan and Their Royal Highnesses Crown Prince Frederik and Crown Princess Mary of Denmark.
Crown Prince Hussein and Rajwa Al Saif will be married in an Islamic marriage ceremony known as "katb ktab" in the gardens at Zahran Palace in Amman, Jordan on Thursday at 2pm UK time. Around 140 guests will be in attendance at the nuptials.
The newlyweds will then travel from Zahran Palace to Al Husseiniya Palace in a procession known as the Red Motorcade.
A wedding reception will take place at Al Husseiniya Palace with over 1,700 guests in attendance.
The bridal party will be treated to performances by local and regional singers, as well as a choir, Jordanian bands, the national orchestra and folk dance troupes.
The reception will conclude with the bride and groom cutting the wedding cake.
After the main reception, a wedding banquet will take place at Al Husseiniya Palace, which will be attended by members of the Royal Hashemite Family, foreign and Arab heads of states, and high-ranking officials.
The palace says the banquet "will combine the formalities and diplomatic aspects of a state banquet with the joyous celebration and traditions of a wedding ceremony".
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