Karlsplatz ("Charles' Square") is a town square on the border of the first and fourth districts of Vienna. It is one of the most frequented and best connected transportation hubs in Vienna. The Karlskirche is located here.
The first district can be reached either by subway or via Operngasse (a street). The pavilions of the former Karlsplatz Stadtbahn Station remain despite the construction of the U-Bahn system.