Roman Catholic Diocese of Sion Roman Catholic Diocese of Sion The Diocese of Sion (, , ) is a Roman Catholic ecclesiastical territory in the canton of Valais, Switzerland. It is the oldest bishopric in the country and one of the oldest north of the Alps. The history of the Bishops of Sion, of the Abbey of St. Maurice of Valais as a whole are inextricably intertwined. The see was established at Octodurum, now called Martigny, the capital of the Roman province of Alpes Poeninae. The first authentically historical bishop was Saint Theodore/Theodolus (died in 391), who was present at the Council of Aquileia in
Priory of Sion Bérenger Saunière: a mummified corpse, which Hammott claimed to believe is Mary Magdalene, in an underground tomb purportedly connected to both the Knights Templar and the Priory of Sion. In the film, Burgess interviews several people with alleged connections to the Priory of Sion, including a Gino Sandri and Nicolas Haywood. A book by one of the documentary's researchers, Rob Howells, entitled "Inside the Priory of Sion: Revelations from the World's Most Secret Society – Guardians of the Bloodline of Jesus" presented the version of the Priory of Sion as given in the 2008 documentary, which contained several erroneous assertions,