The Karlskirche is a church located on the south side of Karlsplatz, Vienna. The Karlskirche, or St. Charles Church, is one of Vienna's greatest buildings. It is probably the most pretentious church in the whole of Austria. The outstanding white Baroque church with it's two thin towers and green roof is certainly worth a visit. The interior is pleasantly light and covered in colourful fresco's. The aspiring design of architectural elements from ancient Greece ancient Rome, contemporary Rome, and contemporary Vienna are combined by the elder Fischer.

The Baroque building is some 80m/262ft long and 60m/200ft wide. The dome rises to a height of 72m/235ft. It cost 304,000 guilders to build. All countries owing allegiance to the Crown had to contribute to the cost as a fine for the deliberate destruction of the chapel of the Austrian Embassy. There is much to be seen in the church with its tall oval central area, two major side chapels and four smaller chapels in the corners.

The freestanding columns were conceived with at least two functions in mind first of which is to portray scenes from the life of St. Charles, carved in imitation of Trajan's triumphs to emphasize the imperial nature of the building and second is to symbolize the Pillars of Hercules, suggesting the right of the Habsburgs to their lost Spanish territory. There is also a sculpture by Henry Moore, "Hill Archer", in a little pool outside. The green copper dome of the Karlskirche rises 236 feet high, a dramatic landmark on the Viennese skyline.

The church is cared for by a religious order and has long been the parish church as well as the seat of the Catholic student ministry of the Vienna University of Technology.