The Priory of Sion, also known as Prieuré de Sion in French, is a secret society, founded A.D. 1099, claiming such members as Isaac Newton, Victor Hugo, and Leonardo Da Vinci. It is said that the primary purpose of the Priory of Sion is to maintain the truth that Jesus Christ was married to Mary Magdalene and had children with her. These children then intermarried with the Merovingian line of Frankish kings, with the sacred bloodline surviving into modern times.
After becoming a cause célèbre from the late 1960s to the 1980s, the mythical Priory of Sion was exposed as a ludibrium created by Plantard as a framework for his claim of being the Great Monarch prophesied by Nostradamus. Evidence presented in support of its historical existence and activities before 1956 was discovered to have been forged and then planted in various locations around France by Plantard and his accomplices. Nevertheless, many conspiracy theorists still persist in believing that the Priory of Sion is an age-old cabal that conceals a subversive secret.
Between 1961 and 1984, there was a pedigree for the Priory of Sion claiming that it was the offshoot of a real Roman Catholic religious order housed in the Abbey of Our Lady of Mount Zion, which had been founded in the Kingdom of Jerusalem during the First Crusade in 1099 and later absorbed by the Jesuits in 1617. The mistake is often made that this Abbey of Sion was a Priory of Sion, but there is a difference between an abbey and a priory. Calling his original 1956 group "Priory of Sion" presumably gave Plantard the later idea to claim that his organisation had been historically founded by crusading knight Godfrey of Bouillon on Mount Zion near Jerusalem during the Middle Ages.
As with most of what is contained there is very little, if any, evidence that would support these conclusions about the Priory of Sion. The Priory of Sion was founded in 1956, not 1099. The supposed ledgers of members of the Priory of Sion are considered to be fraudulent by most respected historians and scholars. The Da Vinci Code takes the Priory of Sion, attaches unfounded conspiracy theories about its origins and purposes, and uses it as evidence of a vast cover-up of Jesus’ marriage to Mary Magdalene.