Mexico's President Felipe Calderon, second right, walks with Belgium's Crown Prince Philippe as they review the honor guard during a welcoming ceremony for Prince Philippe at Los Pinos presidential residence in Mexico City, Monday, March 23, 2009. Prince Philippe and his wife, Princess Mathilde, are on an official visit to Mexico.
Belgium's Prince Philippe and Princess Mathilde, left, arrive in Mexico City, Sunday, March 22, 2009. Prince Philippe and Princess Mathilde are on an official visit to Mexico.
Mexico's President Felipe Calderon, right, waves as he walks with Belgium's Crown Prince Philippe during a welcoming ceremony for Prince Philippe at Los Pinos presidential residence in Mexico City, Monday, March 23, 2009.
Belgium's Prince Philippe and Princess Mathilde, left, pose for photographers during a visit to the National Anthropological Museum in Mexico City, Sunday, March 22, 2009.
Spain
Spanish Crown Prince Felipe, center, and Crown Princess Letizia, right, listen to Chief Librarian Michael Terry, left, explain a historical document during a visit to the New York Public Library Monday, March 16, 2009, in New York.
Spanish Crown Prince Felipe and Crown Princess Letizia examine a document during a visit to the New York Public Library Monday, March 16, 2009, in New York. They viewed a selection, including the first Spanish edition (1493) of Christopher Columbus' letter describing his first voyage.
Spanish Crown Prince Felipe, center, and Crown Princess Letizia right, listen to Chief Librarian Michael Terry, left, explain a historical document during a visit to the New York Public Library Monday, March 16, 2009, in New York.
Swiss Federal President Pascal Couchepin, left, shakes hands with Spanish artist Miquel Barcelo, right, next to Queen Sofia, second left, and Spain's King Juan Carlos, second right, during the inauguration of the Human Rights Room (Room XX) at the European headquarters of the United Nations in Geneva, Switzerland.
Sweden
Italian President Giorgio Napolitano, left, and Sweden's King Carl XVI Gustaf review the honor guard during their meeting at Quirinale, the presidential palace, in Rome, Tuesday, March 24, 2009.
Sweden's King Carl XVI Gustaf is saluted by an Italian Presidential guard as he walks with Italian President Giorgio Napolitano, not seen, during their meeting at Quirinale, the presidential palace, in Rome, Tuesday, March 24, 2009.
Rome's Mayor Gianni Alemanno, in foreground, bows before Sweden's Queen Silvia, at left, as she arrives with King Carl XVI Gustaf for a visit to Rome's City Hall, in Rome, Wednesday, March 25, 2009.
Sweden's King Carl XVI Gustaf, second left, flanked by Queen Silvia, left, meets with Italian President Giorgio Napolitano, second right, and his wife, Clio, at Quirinale presidential palace, in Rome, Tuesday March 24, 2009.
Italian premier Silvio Berlusconi, left, talks to Sweden's Queen Silvia during their meeting in Rome's Villa Madama, Wednesday, March 25, 2009.
Italian President Giorgio Napolitano, center, and Sweden's King Carl XVI Gustaf welcome 1986 Nobel prize laureate for Medicine Rita Levi Montalcini at a reception at the Quirinale presidential palace, Wednesday, March 27, 2009. At left is Sweden's Queen Silvia and Napolitano's wife Cleo.
Britain
G20 leaders gathered in London, Wednesday, April 1, 2009, are pictured with Britain's Queen Elizabeth II, center, at London's Buckingham Palace.
First lady Michelle Obama is welcomed by Britain's Queen Elizabeth II, as she arrives with President Obama for an audience at Buckingham Palace in London, Wednesday April 1, 2009.
Britain's Queen Elizabeth II, center, talks with U.S. Secretary of State Hillary Rodham Clinton, left, and French President Nicolas Sarkozy, right, during a reception at London's Buckingham Palace for world leaders attending the G20 summit.
Britain's Prince Charles, left, and his wife Camilla, Duchess of Cornwall, center, meet Secretary of State Hillary Rodham Clinton, right, at London's St. James's Palace, Wednesday, April 1, 2009. Prince Charles hosted a meeting of world leaders on global climate and environmental challenges, ahead of the G20 summit in London.
President Barack Obama meets with King Abdullah of Saudi Arabia at the G20 summit at the ExCel Centre in London, Thursday, April 2, 2009.
Britain's Prince Charles, center, and his wife Camilla, Duchess of Cornwall, right, greet France's President Nicolas Sarkozy, left, at London's St. James's Palace, Wednesday, April 1, 2009. Prince Charles hosted a meeting of world leaders on global climate and environmental challenges, ahead of the G20 summit in London.