I rent my room in the 4th district of Vienna, a very quiet place, next to the city center. You will find the Opera, Belvedere or Naschmarkt very close, you can walk in 10-15 to there. Metro U4 and U1, Tram 1, 62 and Bus 13A are very very close.
The room is around 15 m2 big with a double bed.
The flat also offers a complete bad, a toilet, a kitchen, and a big living room.