St. Stephen's Cathedral is the symbol of Vienna. Construction commenced in the 12th century. Today, it is one of the most important Gothic structures in Austria. St. Stephen's Cathedral is 107.2 meters long and 34.2 meters wide. It has four towers. The tallest of these is the south tower at 136.44 meters. The tower room, from which there is a gigantic view across Vienna, is reached via 343 steps. A total of 13 bells hang here. However, the best-known bell of St. Stephen's Cathedral, the Pummerin, is located in the 68.3 meter-tall north tower. It is the second-biggest free-swinging chimed church bell in Europe. On the roof of St. Stephen's Cathedral, colorful roof tiles were laid to create the Royal and Imperial double-headed eagle and the coat of arms of the city of Vienna. The interior of St. Stephen's Cathedral was changed again and again over the centuries, right through to the Baroque period.
https://www.wien.info/en/sightseeing/sights/st-stephens-cathedral