Completed in 1160, after 23 years of planning and construction, the Viennese St. Stephen's Cathedral is nowadays one of the main attraction of the Austrian capital. Located right in the central first district it's the mother church of the Roman Catholic Archdiocese of Vienna and the seat of the Archbishop of Vienna, Cardinal Christoph Schönborn. An imposing building with a long history during the Habsburg monarchy and an access to the Vienna catacombs, a widely branched underground network with skulls of ancient kings lying around and some pretty gruesome stories. Definitely worth a visit if you are in Vienna!