I had a lovely stay at Christiana's place. The apartment is beautiful, and well located. The city center was a 15-20 minute scenic stroll which was great for exploring. The apartment is located close to the main train-line you'd use to get around Vienna city center, so public transport is a great option as well. There's also a bunch of different places to eat, and consume coffee very close to Christiana's. I would stay here again next time I'm in Vienna.