Last time I was in Vienna on a day trip from Salzburg, it was the middle of summer. I went out to Schloss Schönbrunn with very little expectation (I think on some kind of tour bus, if I remember right?) and checked out the grounds and museum. Coming back for the Christmas market was something else, especially with a thick fog making everything glow spectacularly. The metro ride is like 15min and €2, so skip the bus. 🌟🎄❄️