St. Stephen's Cathedral (Stephansdom)

St. Stephen's Cathedral has anchored Vienna's skyline since the 12th century, though most of the Gothic building visitors see today dates from the 14th and 15th centuries, built over an earlier Romanesque church whose west facade and Giant's Doorway survive at the main entrance. Its most photographed feature is the roof: 230,000 glazed tiles arranged in a bold zigzag pattern and, on the north side, a mosaic of the double-headed Habsburg eagle.

The south tower — nicknamed "Steffl" — rises 137 metres and remains unfinished on the northern side, where a matching tower was never completed; climbing its 343 spiral steps rewards visitors with the best rooftop view over Vienna's Old Town. The north tower instead holds the Pummerin, Austria's largest bell, reachable by elevator. Below ground, catacombs hold centuries of burials, including urns containing the internal organs of Habsburg rulers — their bodies went to the Kapuzinergruft crypt, their hearts to the Augustinerkirche, in a deliberately split burial tradition unique to the dynasty.