During your visit to Vienna you will notice that much of the magnificent Baroque buildings in the city are the work of a tireless artist named Johann Fischer von Erlach. The Karlskirche is no exception. Many consider it to be the most sublime Baroque church in the city.

The Karlskirche was built with two objectives. On the one hand, the Emperor Charles VI made a promise that when the city was free from the terrible plague of 1713, he would erect a votive temple dedicated to San Carlos Borromeo. Former archbishop of Milan and known patron of the fight against the epidemic. On the other hand, it is a glorification of the Catholic faith that both defended the monarchs of the Habsburg dynasty and also connects to the patron of the church, since he was an outstanding fighter against the Reformation. 

Dominated by an eclectic aesthetic, which combines classical elements reminiscent of Greek and Roman architecture with parts that show the clear influence of the East, works to build the Karlskirche began in 1716 and ended in 1737, so that after the death of Fischer von Erlach in 1723, his son Joseph Emmanuel was responsible for completing the project.

The church's different influences are reflected mainly in the façade. 

It is full of symbols. To glorify the Christian faith you can see on both sides of the stairs two angels representing the Old and New Testaments. On top of the gable and in the side halls there are sculptures representing the theological virtues of faith, hope and charity.

From the outset, it may seem very similar to the Italian Renaissance basilicas, namely San Pedro in Rome. However, if you look closely, Fischer von Erlach is taking a risky architectural chance.

The stylistic combination proposes giving access to the faithful through what could be the porch of a Greek temple whose pediment by Giovanni Stanetti (in which the suffering of the Viennese during the plague is shown) is topped by a statue of the patron saint of the church. 

The great dome is framed by two columns that do not hide their inspiration, Trajan's Column in Rome. Even in the outline of the spiral bas-reliefs, which in this case narrate scenes from the life of San Carlos Borromeo, consistency is the overall theme on the left and it is moral strength on the right. But there is a clear Arab influence; these columns are topped so that, from a distance, they might look like minarets. A second reading of these columns reveals another symbol with a double meaning, that of the power of the Habsburgs, because they make clear reference to the columns of Hercules that this mythical hero built in southern Spain and Carlos V placed in his coat of arms. Interestingly, perseverance and moral strength "Constantia et fortitudo" was the motto of Charles VI.

Surprising as it may seem, it is evident that the side halls of the temple refer to the architecture of Chinese pagodas, which definitely raises Fischer von Erlach to the category of genius in the synthesis of styles.

Inside, like any self-respecting baroque church, it boasts rich pictorial and sculptural decoration both by the most famous artists of the moment, which is adorned with beautiful polychrome marbles. 

The high altar by Alberto Camesina, has a stucco relief with San Carlos Borromeo on a cloud rising into heaven surrounded by angels. 

In addition to the carvings and altarpieces by painters Daniel Gran and Altomonte Martino, there are portentous frescoes inside the dome, which, although this is not obvious from afar, are oval-shaped. 

The Apotheosis of San Carlos Borromeo is represented and was painted between 1725 and 1730 by Johann Michael Rottmayr and you can see San Carlos Borromeo and the Virgin imploring the Holy Trinity to end the plague. Rottmayr was also responsible for the frescoes located above the organ, depicting Santa Cecilia among the musical angels. This would be the last commission that he would complete before dying on 25th October 1730.

You can also see a magnificent golden pulpit richly decorated with garlands of flowers and two beautiful angels topping the canopy. A magnificent organ, the choir seats and beautiful baroque confessionals. Among the most remarkable pieces of treasure in the church are the garments of San Carlos Borromeo and a beautiful gold and silver reliquary decorated with the imperial crown and the double eagle of the Habsburgs.

Although it has sometimes been criticized for its extravagance because of its mix of styles, the Karslkirche is key to understanding the development of Habsburg Vienna during the halcyon years following the end of the Turkish threat in 1683, and also enjoys one of Vienna's most splendid baroque buildings.