Re-Education Centre by adding a second floor. This includes a balcony to the front. In line with my drive for "accuracy" you might think I've forgotten to provide a door out to the balcony, but the first floor doesn't extend as far as the ground floor - suggesting that the door would have been in the now ruined section. The same could be said of the stairs, and I suppose this should be taken into account when it comes to adding rubble and the like!
When adding extra parts (an entire storey in this case) it's important to keep the continuity of the story of the building. What this means is to ensure that damage flows through as you might expect. Looking at the first image below you can see the the bottom of the first floor (that's the top one because I'm not American!) has no damage, even though it sits above the quite damaged ground floor (that's the bottom one for any Americans reading!). This just wouldn't do, so I attacked the new part of the building with a pair of clippers. I think that it is this sort of minor attention to detail that is easily missed, but can make a big difference to the "believe-ability" of the buildings.