The Church of St Charles Borromeo, or Karlskirche, is the finest baroque church in Vienna and was built between 1716 and 1739, after a vow by Karl VI at the end of the 1713 plague. It was designed and commenced by Johann Bernhard Fischer von Erlach and completed by his son Joseph. Although predominantly baroque, it combines several architectural styles.

The twin columns are modeled on Trajan's Column in Rome and show scenes from the life of St Charles Borromeo (who helped plague victims in Italy), to whom the church is dedicated. The huge oval dome reaches 236 ft (72m); in combination with the church's large windows, the dome's height creates a bright, open nave. There is a small museum with a handful of religious art and clothing purportedly from the saint, but the highlight is the lift to the dome for a close-up view of the detailed frescoes by Johann Michael Rottmayr. The altar panel is by Sebastiano Ricci and shows the Assumption of the Virgin. In front of the church is a pond, complete with a Henry Moore sculpture from 1978.