St. Stephen's Cathedral (Stephansdom in German) is a Gothic cathedral located in the heart of Vienna, Austria. It is the mother church of the Archdiocese of Vienna and one of the most iconic landmarks of the city. The construction of the cathedral started in the 12th century and it was completed in the 15th century. The cathedral has undergone several renovations and restorations over the centuries, most notably in the 18th and 19th centuries.

St. Stephen's Cathedral is known for its distinctive multicolored tile roof, which is covered with over 230,000 glazed tiles arranged in a pattern of diamonds and eagles. The cathedral's interior is equally impressive, with its soaring vaulted ceilings, stained glass windows, and intricate stone carvings. Visitors can explore the cathedral's many chapels and altars, as well as climb the 343 steps to the top of the south tower for panoramic views of the city.

One of the most famous features of St. Stephen's Cathedral is its massive bell, the Pummerin, which weighs over 21,000 kilograms (46,000 pounds). The bell is rung only on special occasions, such as New Year's Eve and Easter.

St. Stephen's Cathedral has played an important role in Austrian history and culture. It has been the site of many important events, including royal weddings and funerals, and is the final resting place of many notable Austrians. The cathedral is also home to an extensive collection of religious artifacts and treasures, including the medieval pulpit by Anton Pilgram and the Riesensaal ("Hall of the Giants"), which houses the cathedral's giant bells.