In the early hours of March 4, 1924, a middle-aged man and his family left the Dolmabahce Palace in central Istanbul and headed to the train station. Their destination was Switzerland and then Paris, where the man, Abdulmecid II, died 20 years later, and was buried in Medina. Abdulmecid II was the last caliph of Islam, the end of a line of religious and political rulers that had stretched back unbroken to the time of the Prophet Mohammed.