Pope Benedict arrives in Istanbul on Tuesday to meet with the Istanbul-based head of the world's 250 million Orthodox Christians, along with Turkey's prime minister.
But tensions are high in the predominately Muslim country, after the pope quoted a Byzantine emperor who characterized some of the teachings of Islam's Prophet Muhammad as "evil and inhuman."
Security will be tight for the papal visit. Over the weekend, a crowd of 25,000 turned out in Istanbul, urging the pope to stay home. There were smaller protests Monday.
Pope Benedict's trip was originally planned as part of an effort to mend a thousand-year-old rift between Catholics and Orthodox Christians.