The Priory of Sion: Myth or Reality?

The Priory of Sion, is a name given to multiple groups, both real and fictitious. It was a organisation created in 1956 by Pierre Plantard.
In the 1960s, Plantard created a fictitious history for that organization, describing it as a secret society founded in the Kingdom of Jerusalem in 1099, which serves the interests of the Merovingian dynasty and its alleged bloodlines. This myth was expanded and popularized by the 1982 controversial book The Holy Blood and the Holy Grail, written by Dan Brown, later claimed as factual in the preface of the 2003 conspiracy fiction novel The Da Vinci Code. The Priory of Sion is portrayed in the book as an ancient, powerful organization guarding a historical secret of great importance. According to Dan Brown the Priory preserved the truth about Jesus and Mary Magdalene for centuries. Isaac Newton, Sandro Botticelli, Victor Hugo and da Vinci all belonged to the Priory.
Many conspiracy theorists persist in believing that the Priory of Sion is an age-old cabal that conceals a subversive secret.