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 Valais chose Sierre. In 1840, the Upper and Lower Valais were reunited. But four years later, Sion was occupied by Upper Valais troops during the beginning of the Sonderbund War. Federal troops occupied Sion in November 1847. Sion lost to Turin, Italy in its bid to host the 2006 Winter Olympics. Sion also bid for the 2002 Winter Olympics, which it lost to Salt Lake City, and the 1976 Winter Olympics, which it lost to Denver (the games were reassigned to Innsbruck when Denver residents voted down additional funding). As of February 2018, Sion is one of four cities participating