Constantine's place is great! It's a completely-renovated modern apartment in a quiet older building. Plus it serves as an art gallery for his own photography- of which he has a number of attractive pieces. It certainly adds a nice personal touch to the place.
Constantin greeted us personally to check us in. He also recommended his favorite nearby places which were spot on. And, as we were there for a month, he offered to arranged weekly cleanings for us. He was most gracious and very helpful. All in all it worked out quite well.
The location was just perfect! We were able to walk to most places in the inner city, or simply take the subway from the nearby station.
Speaking of nearby: be sure to take a tour of the Rathaus, since it's across the street, and it's free, and it's extraordinary. Also the Musa on the corner. It's a quirky modern art museum- as well as an art "library".
Constantin's Sky Gallery is a fantastic place to come home to after a long day of touring the grand palaces of Vienna. Another one of our favorite places in Europe.