Scenario ideas:
1 - The low-ish apartment buildings along Prospekt Lenina (as was) just riverwards of Barrikady gun factory - househopping north by the Germans and later south by the Russians.
2 - Mamayev Kurgan - one day someone is going to make this. Combined arms over winter trenches on a huge great dome-shaped hill.
3 - Tsaritsa gorge - big old balka with apartment blocks on either side - killing fields aplenty.
Design notes for house-to-house:
Buildings in the centre were pretty tall (5-6 stories) and had a partially underground basement with windows which looked out below street level (into a kind of hole) So the 1st or ground floor was 1 metre or so above ground level.
The centre would be the area with more relatively intact buildings due to them being tougher, although more of these would be town admin buildings etc. where you would have slightly more leeway in terms of floor plan.
In some areas not far off the centre (e.g. just north of the station there were buildings more like this:
http://content.cdlib.org/xtf/data/13030/bj/ft1g5004bj/figures/ft1g5004bj_00015.jpg
The thing about most of the bitter house to house fighting is that it usually did not take place down long, snakey corridors with nice rifle ranges along the corridor. The standard engagement distance in these places was such that an SMG, nade or sharpened spade was your best hope of survival.
In residential areas each building would have several seperate, autonomous entrances - these lead to one flight of stairs, maybe with an elevator in the more luxurious buildings (although that would usually be a steel cage -type of thing in the 40's).
So each flight of stairs would have 2,3 or 4 flats on each floor - these would be 2,3 or 4 room with a balcony, maybe very narrow, off one of the rooms. The WC and bathroom would usually be seperate and would not have exterior windows - they would be in the centre of the building, near the stairwell.
This
Bulgarian property gives you a bit of an idea of the layout - although the Russian apts would have seperate kitchens. Also look at
section B of this picture
Once you've planned out the building, then knock it down. The interior floors and ceilings were the first things to go from bombs, interior walls were a bit tougher, with the exterior walls going next and the stairwells, being concrete, actually being quite tough and surviving quite well nutil they fell over from lack of support. Mouseholes were common between the seperate stairwell units' flats. having said that, I have seen quite a few surviving apartment blocks with concrete stairwell floors with filler in grenade holes which were gouged out of the surface.
The exterior walls were red brick either under a layer of tan, cream or ochre stucco or bare. Either way, huge piles of red bricks all over the place are a necessity.