Question: What is the name of the town square that is on the border of the first and fourth districts of Vienna and one of the most frequented and best connected transportation hubs in Vienna, the location of Karlskirche which is  widely considered the most outstanding baroque church in Vienna?
Sentence (from "Karlskirche"): Karlskirche (St. Charles's Church) is a baroque church located on the south side of Karlsplatz in Vienna, Austria.
Relevant evidence: No