Definitely worth the visit. Absolutely gorgeous place with amazing paintings. Since they are renovating the church, it is possible to take an elevator to the top of the dome so you can enjoy the beautiful artwork up close. Do not hesitate to take the elevator, you won’t regret it. If you aren’t afraid of hights you can climb even further up, to the lantern. The view is not worth it, but it is an exciting climb nonetheless. This church is an exquisite piece of architecture.

Karlskirche, Kreuzherrengasse 1 Karlsplatz/Belevedere Quarter, Vienna 1040, Austria
http://www.karlskirche.at/
+43 1 5046187

Visited June 2014. You can find my review about Karlskirche also on TripAdvisor.