Princess Grace's grandson to wed longtime girlfriend 

Aug. 7, 2013 at 10:31 AM ET

CAP D'ANTIBES, FRANCE - MAY 23: (Premium Rates Apply) Tatiana Santo Domingo and Andreas Casiraghi attend de Grisogono Glam Extravaganza at Hotel Du Ca...
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Tatiana Santo Domingo and Andreas Casiraghi attend an event at the Hotel Du Cap Eden-Roc on May 23, 2012 in Cap D'Antibes, France.

Save the date: It's time for another royal wedding! Later this month, Andrea Casiraghi, the son of Princess Caroline and grandson of the late Princess Grace, will wed his longtime girlfriend, Tatiana Santo Domingo. 

"The wedding will take place on August 31," a spokesperson for the Palace of Monaco told in an e-mail. 

The fashionable couple met as schoolmates at Paris' Lycée Fontainebleau, and dated for seven years before announcing their engagement in July 2012. Their son, Sacha, was born last March. 

** FILE ** Prince Rainier III of Monaco and Princess Grace, holding Princess Stephanie, pose with their children on the palace steps in Monaco, France...
Prince Rainier III and Casiraghi's grandmother, Princess Grace, pose on the palace steps with their children in April 1966. Prince Albert sits on the left with Casiraghi's mother, Princess Caroline (center).

Casiraghi is Princess Caroline's eldest son, and though he is without an official royal title, the 29-year-old is second in line to the Monegasque throne. That's because Prince Albert II, Monaco's current ruling sovereign, cannot pass the crown down to his two children, who were both born out of wedlock. Until the prince has a child with wife Charlene Wittstock, Princess Caroline will remain the heiress presumptive to the throne and her son second in the line of succession. 

The bride-to-be, also 29, may not be royalty, but her family is a prominent one in Colombia, where her father, Julio Mario Santo Domingo, Jr., is the second richest man, according to Forbes magazine. The Swiss-born Tatiana is the co-founder of eco-friendly fashion line Muzungu Sisters and is a fixture of the New York City social scene. 

The wedding is slated to be a private event, according to the palace spokesperson.

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