Roman's house is perfect for visiting Vienna.
It stands in front of one of the Danube channel and is walking distance from the true historical center of the city: St. Stephan cathedral, Imperial palaces including Hofburg and Museums Quartier district. The underground station is few meters along and various restaurants and cafes are just on the channel other side.
Roman is highly responsive and available to fit personal requests, if and when possible. His house is a jump back in the 70’s but with all modern comforts; it is very clean, and may accommodate 3-4 adults even though with a single bathroom.
You’ll enjoy your staying in Vienna.