Natalie's apartment is well located next to Vienna's train station, which allows you to easily visit Vienna. We would also recommend visiting the St. Francis of Assisi Church next to the apartment, especially after sunset.
Walid was very responsive during our stay. On the first day, he planned for us the different monuments that we should see in Vienna, and even draw an itinerary on a map for us, corresponding to the number of days we were staying in Vienna.