Belgium’s future Queen, Princess Elisabeth, is set to attend Prince Christian of Denmark’s 18th birthday celebration this month. The Belgian Royal Palace confirmed on Oct. 5 that King Philippe and Queen Mathilde’s eldest child will travel to Copenhagen for Christian’s birthday gala dinner.

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Queen Margrethe II of Denmark is hosting the event for her grandson, who is second in line to the Danish throne, on Oct. 15 at Christiansborg Palace. Elisabeth isn’t the only future monarch who will be in attendance.

Princess Ingrid Alexandra of Norway, who is second in line to the Norwegian throne, will be attending the gala dinner with her father, Crown Prince Haakon. Christian’s godmotherCrown Princess Victoria of Sweden will also attend the celebration with her husband Prince Daniel.

Last week, the Danish Royal House shared a video of invitations being printed and packaged for Christian’s birthday. According to Gert’s Royals, the invitation states that the dress code is “Galla B (B meaning Ballgown)/Uniforms/ White tie/ Gowns” and that “Decorations (Honors) and Tiaras may be worn.”

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Princess Elisabeth made her tiara debut last year at Princess Ingrid Alexandra’s 18th birthday gala dinner. Meanwhile, the Norwegian Princess was photographed wearing a tiara for the first time in portraits to mark her 18th birthday.

Prince Christian will celebrate his 18th birthday on Oct. 15. Hours before his birthday gala dinner that Sunday, the Prince will appear on the balcony of Frederik VIII’s Palace with his family and Queen Margrethe.