The Diocese of St. Gallen is a Roman Catholic diocese located in eastern Switzerland. Established in the 8th century, it has a rich history and plays a significant role in the spiritual life of the region. The diocese is named after its patron saint, Saint Gallus, who founded a monastery in the area. The diocese covers a diverse geographical area, including parts of the cantons of St. Gallen, Appenzell Innerrhoden, and Thurgau. It is part of the ecclesiastical province of Basel and is known for its cultural heritage, including the famous St. Gallen Abbey, a UNESCO World Heritage site.