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
Sion, Switzerland recreational space in the municipality increased by and is now about 4.47% of the total area. Of the agricultural land, is used for orchards and vineyards, is fields and grasslands and consists of alpine grazing areas. Since 1980 the amount of agricultural land has decreased by . Over the same time period the amount of forested land has increased by . Rivers and lakes cover in the municipality. Sion has an average of 82.6 days of rain or snow per year and on average receives of precipitation. The wettest month is December during which time Sion receives an average of