We hadn’t meant to visit Karlskirche, but wandered past it as we were making our way towards the Schloss Belvedere. It was even an arbitrary decision to enter, paying a few euros each to do so, but once inside we knew it was well worth it. Whereas the interiors of most of the other public buildings and churches we visited in Vienna were far too ornate for my taste, Karlskirche avoided gaudiness, just about.
The interior is currently being renovated and scaffolding has been erected that reaches into the central dome. A lift carries visitors up to a platform from where the remarkable frescos that cover the inside of the dome can be viewed at close quarters. A further set of stairs allows you to climb up to the top of the dome, and peer out over the city.