Well HDR makes it so whenever you are in a dark area, it'll adjust the lighting to make it brighter and vise versa.

Very nice map! There's absolutely no flaws I can see with this map.

There are 3 tings I would like to suggest.

1 - Colour correction.

I personally think the sun is too white.

2 - Building depth.

The flat walls bordering your map look uninteresting. You would make the buildings stick out more to make them look more real.

3 - More detail behind the windows.

The rooms behind the windows like in your last screen shot have nothing in them. Just a chair or stool. Making those rooms look less empty would give more life to your map.

Asside from those suggestions I do have 1 question for you.

In the last screen shot, The room is very well lit. How exactly did you make it look so lit up when there's no light source asside from the windows?

When ever I have rooms blocked off by sunlight they always look ridiculously dark. (n)