<!-- Image with unknown copyright status removed: -->The Tiara of Pope Gregory XIII is the oldest surviving papal tiara in existence. Its actual date of manufacture is not recorded. It is known however that it was manufactured during the reign of Pope Gregory XIII (1572-1585), the creator of the Gregorian calendar.
Until 1798 many ancient tiaras existed in the Vatican. However invading French troops stole and smashed all the tiaras they could get their hands on, stealing their jewels, which they transported back to Paris. It is unknown how the Gregory XIII's tiara survived the destruction.