Pope Francis leads a mass at the cathedral of the Holy Spirit on November 29, 2014 in Istanbul as part of a three day visit in Turkey. The centrepiece of his morning tour was a closely-scrutinised visit to the great Sultan Ahmet mosque -- known abroad as the Blue Mosque and one of the great masterpieces of Ottoman architecture. The pope paused for two minutes and clasped his hands in reflection alongside a senior Islamic cleric, a gesture remarkably similar to that of his predecessor Benedict XVI who visited the mosque on the last papal visit to Turkey in 2006. AFP PHOTO / FILIPPO MONTEFORTE