text: the gemeindebau "Spittelbreitengasse 23" consists of 10 separate buildings. with a total of 33 units.
  
  https://www.wwpipe.at/web-portal/complex-description/0812357
  
  this is unit 8 of that whole gemeindebau.
  
  56 would be the number when coming from Ruckergasse. it is on the building there too. 
  
  no idea what postal address/street is actually used for each of the buildings within the building complex.