St. Stephen's Cathedral

Founded in 1137 following the Treaty of Mautern, the original Romanesque structure was dedicated to Saint Stephen in 1147. A major reconstruction began after a fire in 1258, resulting in a larger late-Romanesque building whose western facade and towers survive. Extensive Gothic expansions were later initiated by Duke Rudolf IV, who laid the cornerstone for the Gothic extension in 1359, eventually completing the southern tower in 1433.

The cathedral features an ornate, steeply pitched roof tiled with multicolored glazed ceramics creating distinctive geometric and heraldic patterns. The interior houses notable historical artworks, including the late-Gothic Wiener Neustädter Altar crafted in 1447, an elaborately carved stone pulpit, and the marble tomb of Emperor Frederick III. The unfinished north tower houses the famed Pummerin bell, cast from captured Ottoman cannons.

During the final days of World War II in April 1945, adjacent fires spread to the cathedral, destroying the wooden roof framing and historical choir stalls. Protective masonry saved many interior treasures, and a swift post-war restoration culminated in its complete reopening in 1952. The church functions as the mother church and episcopal seat of the Roman Catholic Archdiocese of Vienna.