The picture is almost a case study of the problems of interpreting historical art for historical purposes.
Vischer needed to make money, so he had to generate appealing views if the cities in question; and he worked on a large number of cities in the Hapsburg empire. So he polished up and tightened up the vistas, leaving one to guess as to how accurate they were.
Several cases in point, in no particular order
• the city condition is way too good; the Swedish commander Torsten and his troops had destroyed some 60 houses when taking the city during the 30 Year War, blown corners off the city tower, etc
• the castle of Kreutzenstein is too proximate to the city and in too good a condition, as Torsten had the fortifications blasted before departing
• the Hungarian Gate had additional structures (Vorwerk) that are not depicted
• the relationship to the Danube and the absence of the shipping channels cannot be right
Of course, Vischer got many things right
• one can make out the city tower, the city church St Aegid, and the tower if the Capuccian monestary
• the large buildings in the center are most likely the roof tops of the salt silos
• due to being a landesfürstliche city there were to be no buildings around the outside fortifications, which is what Vischer depicts
But that still leaves two church spires unexplained (the Augustine priory? Private house chapels?) and gives in general no confidence in the specifics of the rooftops depicted.