Al and Mel discuss the time of the inside inscription on the building of the Dome of the Rock in Jerusalem.  Their discussion is built on the article; "The Jewish Serpent King in the Dome of the Rock" by AJ Deus.  AJ says that the inscription on the inside of that building is not 7th century inscription but rather sixteenth century.  They point out that the crusaders were in control of Jerusalem for two centuries (11th and 12th), and that they held Christian services inside the Dome. It is very unlikely that the pope will leave a memorial for Mohammad there. All this is a strong case for a later date.