Pope Francis prepares to free a dove as he arrives at the Istanbul's Holy Spirit Cathedral on November 29, 2014 in Istanbul. On the second day of his first trip to overwhelmingly Muslim but officially secular Turkey, Francis toured key religious and historical sites in the city once known as Constantinople that was conquered by the Ottoman army in 1453. The visit of the pope is seen as a crucial test of Francis's ability to build bridges between faiths amid the rampage by Islamic State (IS) jihadists in Iraq and Syria and concerns over the persecution of Christian minorities in the Middle East. AFP PHOTO/OZAN KOSE