The Stiftskirche St. Gallus und Otmar (Collegiate Church of St. Gall and Otmar) is a Roman Catholic church in the city of St. Gallen, Switzerland.[1] Once part of the Abbey of St. Gall, it has been the cathedral of the Diocese of St. Gallen since 1847.[2] It is considered one of the last great sacred structures of the Baroque era, and is a UNESCO World Heritage site.