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 "Church of St. Casimir, Vilnius"): In 1919 the church of St. Casimir was returned to the Catholics, but was damaged again during the Second World War, closed down and in 1963 converted into a Museum of Atheism.
Relevant evidence: No