Princess Caroline's son Andrea Casiraghi will marry his longtime girlfriend Tatiana Santo Domingo, Monaco's palace announced in a statement.

The palace did not provide a date for the wedding which is expected to be the royal wedding of 2013.

"I'm happy to announce the engagement of my son Andrea Casiraghi to Miss Tatiana Santo Domingo," Princess Caroline, said in a statement.

Casiraghi and Santo Domingo are both 28 years old and have been dating for seven years. Santo Domingo is a half-Brazilian, half-Colombian heiress once dubbed "The World's Most Elegant Woman" a title that was also given to Jackie Kennedy and actress Grace Kelly, the grandmother of his future husband.

She is from one of Colombia's wealthies families with a $6 billion fortune. Her grandfather is the late magnate Julio Mario Santo Domingo.

Santo Domingo has her own Fashion brand "Muzungu Sisters" with friend Dana Alikhani. She speaks Portuguese, Spanish, Italian, French and English.

Casiraghi is Caroline's eldest son. He has three siblings and his father is Stegano Casiraghi who died in a car crash in 1990.

He follows his uncle Prince Albert II of Monaco in the line of succession to the Monaco throne until he has a son.

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