Pope Benedict XVI (C) talks to Prince Albert II of Monaco and his wife Princess Charlene on January 12, 2013 during a private audience at Vatican. AFP PHOTO / VINCENZO PINTO

This handout picture released by the Vatican Press office on December 7, 2012 shows Dieter Zetsche, chairman of Daimler AG, walking with Pope Benedict XVI as he presents to the pontif the new ecologically-friendly "popemobile" which has been vamped up with the latest gadgets for maximum comfort. AFP PHOTO / OSSERVATORE ROMANO / HO RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / OSSERVATORE ROMANO" - NO MARKETING - NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS

Pope Benedict XVI and Cuban President Raul Castro (R) arrive to a protocol hall at Revolution Palace in Havana, on March 27, 2012. Pope Benedict XVI, on the second day of a historic visit to Cuba, headed to Havana where he is to celebrate mass and possibly meet with the island's most famous inhabitant -- former president Fidel Castro. AFP PHOTO/ADALBERTO ROQUE-POOL

Cuban President Raul Castro (R) gestures next to Pope Benedict XVI as they arrive to a protocol hall at the Revolution Palace in Havana, on March 27, 2012. Pope Benedict XVI, on the second day of a historic visit to Cuba, headed to Havana where he is to celebrate mass and possibly meet with the island's most famous inhabitant -- former president Fidel Castro. AFP PHOTO/ADALBERTO ROQUE-POOL

Cuban President Raul Castro (R) shakes hands with Pope Benedict XVI after mass at Revolution Square in Havana on March 28, 2012. Pope Benedict XVI was to meet Fidel Castro as he wraps up a three-day visit in which he called for a more "open society" on the Communist-run island. AFP PHOTO/Juan BARRETO

This handout picture released by the Vatican Press Office shows Pope Benedict XVI with Cuban leader Fidel Castro (L) during a meeting on March 28, 2012 in Havana. Pope Benedict XVI met with Cuba's revolutionary icon Fidel Castro Wednesday, the last day of a trip to bolster the Roman Catholic church's relationship with the Communist government AFP PHOTO / OSSERVATORE ROMANO RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT " AFP PHOTO / OSSERVATORE ROMANO" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS

This handout picture released by the Vatican Press Office shows Pope Benedict XVI with Cuban leader Fidel Castro (L) during a meeting on March 28, 2012 in Havana. Pope Benedict XVI met with Cuba's revolutionary icon Fidel Castro Wednesday, the last day of a trip to bolster the Roman Catholic church's relationship with the Communist government AFP PHOTO / OSSERVATORE ROMANO RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT " AFP PHOTO / OSSERVATORE ROMANO" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS

This handout picture released by the Vatican Press Office shows Pope Benedict XVI with Cuban leader Fidel Castro (L) during a meeting on March 28, 2012 in Havana. Pope Benedict XVI met with Cuba's revolutionary icon Fidel Castro Wednesday, the last day of a trip to bolster the Roman Catholic church's relationship with the Communist government AFP PHOTO / OSSERVATORE ROMANO RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT " AFP PHOTO / OSSERVATORE ROMANO" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS

This handout picture released by the Vatican Press Office shows Pope Benedict XVI with Cuban leader Fidel Castro (L) during a meeting on March 28, 2012 in Havana. Pope Benedict XVI met with Cuba's revolutionary icon Fidel Castro Wednesday, the last day of a trip to bolster the Roman Catholic church's relationship with the Communist government AFP PHOTO / OSSERVATORE ROMANO RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT " AFP PHOTO / OSSERVATORE ROMANO" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS

This handout picture released by the Vatican Press Office shows Pope Benedict XVI with Cuban leader Fidel Castro (R) during a meeting on March 28, 2012 in Havana. Pope Benedict XVI met with Cuba's revolutionary icon Fidel Castro Wednesday, the last day of a trip to bolster the Roman Catholic church's relationship with the Communist government AFP PHOTO / OSSERVATORE ROMANO RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT " AFP PHOTO / OSSERVATORE ROMANO" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS

Handout picture released by Cuban website www.cubadebate.cu showing Pope Benedict XVI (R) with Cuban leader Fidel Castro (L) during a meeting on March 28, 2012 in Havana. Pope Benedict XVI met with Cuba's revolutionary icon Fidel Castro Wednesday, the last day of a trip to bolster the Roman Catholic church's relationship with the Communist government. AFP PHOTO / WWW.CUBADEBATE.CU - ALEX CASTRO

In this picture made available by the Vatican newspaper Osservatore Romano, Pope Benedict XVI, right, meets with Fidel Castro in Havana, Cuba, Wednesday March 28, 2012. (AP Photo/Osservatore Romano)

In this picture made available by the Vatican newspaper Osservatore Romano Pope Benedict XVI, right, meets with Cuban leader Fidel Castro in Havana, Wednesday, March 28, 2012. (AP Photo/Osservatore Romano)

In this picture made available by the Vatican newspaper Osservatore Romano Pope Benedict XVI meets with Fidel Castro in Havana, Wednesday, March 28, 2012. (AP Photo/Osservatore Romano)

(FILES) - Picture taken on March 28, 2012 in Havana of and released by the Vatican Press Office shows Pope Benedict XVI with Cuban leader Fidel Castro (L). Pope Benedict XVI announced on February 11, 2013 he will resign as leader of the world's 1.1 billion Catholics on February 28 because his age prevented him from carrying out his duties -- an unprecedented move in the modern history of the Catholic Church. AFP PHOTO / OSSERVATORE ROMANO

Cuba's President Raul Castro, right, speaks to Pope Benedict XVI, left, after a meeting in Havana, Cuba, Tuesday, March 27, 2012. (AP Photo/Javier Galeano)

In this picture made available by the Vatican newspaper Osservatore Romano Wednesday, March 28, 2012, Cuba's President Raul Castro, center, and Pope Benedict XVI look at a replica of Tolomeus Geography book that the pontiff presented to Castro during a meeting in Havana, Cuba, Tuesday, March 27, 2012. The meeting took place behind closed doors on the pontiff's second day on the island. (AP Photo/Osservatore Romano)

Cuba's President Raul Castro, right, and Pope Benedict XVI meet in Havana, Cuba, Tuesday, March 27, 2012. The meeting took place behind closed doors on the pontiff's second day on the island. (AP Photo/Adalberto Roque, Pool)

German Chancellor Angela Merkel (L) shakes hands with German-born Pope Benedict XVI as they met at the Chancellery in Berlin on September 22, 2011, the first day of the Pontiff's first state visit to his native Germany. The 84-year old pope, German born Joseph Ratzinger, has a packed program, with 18 sermons and speeches planned for his four-day tri p to Berlin, Erfurt in the ex-German Democratic Republic and Freiburg. AFP PHOTO / CZAREK SOKOLOWSKI

German Chancellor Angela Merkel (R) speaks with German-born Pope Benedict XVI as they met at the Chancellery in Berlin on September 22, 2011, the first day of the Pontiff's first state visit to his native Germany. The 84-year old pope, German born Joseph Ratzinger, has a packed program, with 18 sermons and speeches planned for his four-day tri p to Berlin, Erfurt in the ex-German Democratic Republic and Freiburg. AFP PHOTO / CZAREK SOKOLOWSKI