Pierre Casiraghi

Pierre Casiraghi arrives at the Replay Party during the 63rd Annual Cannes Film Festival at Style Star Lounge on May 19, 2010, in Cannes, France.

From left, Pierre Casiraghi, Charlotte Casiraghi and Andrea Casiraghi, the children of Princess Caroline of Hanover, arrive for a dinner at Opera terraces after the religious wedding ceremony of Prince Albert II on July 2, 2011, in Monaco.

Special Section: Monaco royal wedding

Prince Albert II of Monaco, second from right, and his sister Princess Caroline of Hanover, right, attend the Ballets Russes dance company 100th anniversary gala on Dec. 20, 2002, with her children, from left, Andrea Casiraghi, Charlotte Casiraghi and Pierre Casiraghi.

Most beautiful royals in the world

Prince Albert II of Monaco and Princess Stephanie of Monaco with Prince Pierre Casiraghi are seen at the opera of Monaco during the Monaco's national day ceremony, Monday, Nov. 19, 2007.

Two children of Princess Caroline of Hanover, Charlotte Casiraghi and brother Pierre, arrive for the Rose Ball on March 29, 2008, in Monaco. They are next in line to the throne of Monaco after their mom and brother, Andrea.

2008 Rose Ball

Pierre Casiraghi, son of Princess Caroline of Hanover, is seen with his sister Charlotte Casiraghi at the Rose Ball on March 28, 2009, in Monaco. He and writer Beatrice Borromeo were on that year's list of four best-dressed couples.

2009 Rose Ball

From left, Prince Ernst August of Hanover, Princess Alexandra of Hanover, Princess Caroline of Hanover, Charlotte Casiraghi, Prince Albert II of Monaco, Andrea Casiraghi and Pierre Casiraghi are seen at the Prince's Palace as part of Monaco's National Day celebrations on Nov. 19, 2008, in Monaco.

Pierre Casiraghi and Countess Beatrice Borromeo arrive at the Monaco Formula One Grand Prix dinner on May 16, 2010, in Monaco.

Melanie of Massy, Pierre Casiraghi and Princess Alexandra of Hanover attend the Army Parade as part of Monaco's National Day celebrations on Nov. 19, 2010, in Monaco.

Prince Albert II of Monaco, right, and his nephew Pierre Casiraghi watch Handball during day 6 of the 2nd Asian Beach Games at Al-Musannah Sports City on Dec. 13, 2010, in Muscat, Oman.

Most beautiful royals in the world

From left, Pierre Frolla, Andrea Casiraghi and Pierre Casiraghi attend "Peace & Sport - Operation Poseidon" on May 27, 2011, in Monaco.

Children of Princess Caroline of Hanover, Charlotte Casiraghi, left, Andrea Casiraghi, right, and Pierre Casiraghi, leave the Monaco cathedral during the funeral of Princess Antoinette, late Prince Rainier's sister, on March 24, 2011.

Andrea Casiraghi delivers a speech as Pierre Casiraghi, left, and Charlotte Casiraghi look on during the Monaco Rose Ball 2011 on March 19, 2011, in Monte Carlo.

Pierre Casiraghi controls the ball during a charity football match between Prince Albert's Star Team and the F1 "Nazionale Piloti" drivers' team, on May 11, 2010, in Monaco.

Most beautiful royals in the world

Pierre Casiraghi and girlfriend Countess Beatrice Boromeo arrive for the annual Rose Ball at the Monte-Carlo Sporting Club in Monaco on March 27, 2010.

Prince Albert II of Monaco, right, his girlfriend South African swimmer Charlene Wittstock, and his nephew Pierre Casiraghi (waving), swim in the Mediterranean sea on Dec. 20, 2009, in Monaco.

Pierre Casiraghi attends the annual traditional Thanksgiving Mass as part of Monaco's National Day celebrations at Cathedral Notre Dame on Nov. 19, 2009, in Monaco.

Pierre Casiraghi, Princess Caroline of Hanover and Princess Alexandra of Hanover watch from a balcony the Army Parade as part of Monaco's 2007 National Day celebration.

Most beautiful royals in the world

Pierre Casiraghi, left, walks in the pit lane during the Monaco Formula One Grand Prix at the Monte Carlo Circuit on May 27, 2007, in Monte Carlo.

Prince Pierre Casiraghi, son of Princess Caroline of Hanover, leaves Hotel Eden in Rome July 6, 2007, for the celebration of the 45th anniversary of Italian fashion designer Valentino.

Andrea Casiraghi, left, and his brother Pierre walk during the funeral procession for their grandfather, late Prince Rainier III, April 17, 2005, in Monaco.

Princess Caroline of Monaco poses with newborn son Pierre, husband Stefano Casiraghi, center, with daughter Charlotte, and brother Albert with son Andrea, in this 1987 photo.

Most beautiful royals in the world

From left in rear, Prince Albert II, Prince Rainier III and Princess Caroline pose with her three children, from left in front, Pierre, Andrea and Charlotte, on the palace balcony during the national day ceremony, Nov. 19, 1993, in Monaco.

Princess Caroline of Monaco poses for the photographers at the Princess Grace Hospital in 1987 with her baby Pierre, and her father Prince Rainier III, right, her husband Stefano Casiraghi, second left, holding their daughter Charlotte, and her brother Prince Albert II holding their oldest child, Andrea.

Special Section: Monaco royal wedding