Thanks Andrei and Florian for the pleasant stay. The apartment is very very comfortable and particular, it looks like a real nest. If I return to Vienna I would come back here. May be usuful to know that the apartment is close to Plimgramgasse stop station of the U4 line but until the end of january 2020 this stop station will be closed. Anyway, the house of Andrei is attainable by walking (650 meters) from the Kettenbruckengasse station.