Which Baroque architect designed the Karlskirche in Vienna?

Johann Bernhard Fischer von Erlach designed the Karlskirche in Vienna.

The church was commissioned by Emperor Charles VI after the plague epidemic of 1713 and dedicated to Saint Charles Borromeo, the emperor's namesake and a patron invoked against the plague. Fischer von Erlach won the design competition in 1715, and construction began the following year.

The Karlskirche is a striking synthesis of historical references. Its central portico recalls a Roman temple, while the two monumental columns evoke Trajan's Column in Rome and carry reliefs depicting episodes from Saint Charles Borromeo's life. The dome and overall massing also draw on Roman and Byzantine architectural ideas.

Fischer von Erlach died in 1723, before the church was finished. His son, Joseph Emanuel Fischer von Erlach, continued the project and completed it in 1739. That later involvement can cause confusion, but the original design and principal architectural authorship belong to Johann Bernhard Fischer von Erlach, one of the leading architects of the Austrian Baroque.