Pope Benedict XVI (37 images)

Pope Benedict XVI waves upon arrival at Andrews Air Force Base outside of Washington on April 15, 2008. On Wednesday Pope Benedict XVI will visit the White House and on Thursday he will he will say Mass at the Nationals Baseball stadium. (UPI Photo/Mark Wilson/POOL)

Pope Benedict XVI waves as he deboards his airplane after arriving on his first visit to the United States at Andrew Air Force base outside of Washington on April 15, 2008. (UPI Photo/Kevin Dietsch)

U.S. President George W. Bush and First Lady Laura Bush greet walks with Pope Benedict XVI on his first visit to the United States as he arrives at Andrews Air Force Base outside of Washington on April 15, 2008. (UPI Photo/Roger L. Wollenberg)

Pope Benedict XVI and U.S. President George W. Bush listen to the U.S. National Anthem during a welcoming ceremony on the South Lawn of the White House in Washington, on April 16, 2008. The Pope, who is celebrating his 81st birthday today, is on a six day visit to the U.S. (UPI Photo/Shawn Thew/POOL)