In 1713, the Black Plague swept through Vienna. Emperor Charles VI made a vow: if the plague left the city, he would build a church dedicated to his namesake, St. Charles Borromeo. St. Charles was a 16th-century Italian bishop famous for ministering to Milanese plague victims.
The emperor’s prayer was answered, and construction on the church began in 1715. The Karlskirche was built on what was then the bank of the River Wien and is now the southeast corner of a park complex.
The Baroque master Johann Bernard Fischer von Erlach did the original work from 1716 to 1722. After his death in 1723, his son took over and saw the project through to completion in 1737. J. M. Rottmayr painted many of the frescoes inside the church from 1725 to 1730.