Pitchblack inside, lighter shadows outside?

Hi!

I wonder, how could I make some areas very dark, and some areas (mainly outside) lighter? I mean, I don't like that outside areas have to have almost black shadow (shadow strength = 1) to achieve that result. I set ambient light to (0,0,0,255).

I want some places totally dark. How should I achieve this? Do I have to set something on the lightmapper? I don't care about the lightmap calculation speed if there is a good setting.