St. Stephen's Cathedral (Stephansdom) is the mother church of the Roman Catholic Archdiocese of Vienna and the seat of the Archbishop of Vienna, The current Romanesque and Gothic form of the cathedral, seen today in the Stephansplatz, was largely initiated by Duke Rudolf IV (1339–1365) and stands on the ruins of two earlier churches, the first a parish church consecrated in 1147. The most important religious building in Austria's capital, St. Stephen's Cathedral has borne witness to many important events in that nation's history and has, with its multi-coloured tile roof, become one of the city's most recognizable symbols. By the middle of the 12th century, Vienna had become an important center of German civilisation in eastern Europe, and the four existing churches, including only one parish church, no longer met the town's religious needs. Excavations for a heating system in 2000 revealed graves 2.5 meters below the surface, which were carbon-dated to the 4th century indicating a church from that era was present from ancient times. The church was dedicated to St. Stephen, who was also the patron of the bishop's cathedral in Passau, and was oriented toward the sunrise on his feast day of 26 December, as the position stood in the year that construction began.