One way to prepare an urban area for defense is to intentionally conduct a rubbling of the buildings.

With regard to Stalingrad specifically though, once the entire city is essentially been obliterated what are you fighting for, especially as the attacker? The conventional received wisdom that I read about a lot says that the Stalingrad obsession had to do mostly with the the city bearing the name of Stalin and the political and psychological ramifications of that. but if a city does have a large number of enemy troops in it thinking in terms of West Berlin during the Cold war or maybe parts of Stalingrad during world war II can an attacker afford to leave it back there as he continues forward? I don't know just wondering out loud.