Graz Cathedral, also called St. Giles’ Cathedral, is the cathedral church in the Austrian city of Graz, dedicated to Saint Giles. It is the seat of the bishop of the Steiermark diocese, called the Diocese of Graz-Seckau. The church was built in 1438-62 by Friederick III in the Gothic architecture. Nearby is Mausoleum of Emperor Ferdinand II.

More details: https://en.wikipedia.org/wiki/Graz_Cathedral