Baron you are absolutely right.
About the texture: the metal makes for a nice echo when the grenades explode.
The architecture: exactly as the game i based the map on.
Cubemaps: Never got to this stage. It's just a fun map but within the constraints placed upon me by the game layout there is no room to make it a great map so this is as done as it will get.
First thing that struck me was the fact that there seems to be only one texture for the entire map. The second thing was that there are no cubemaps. The architecture is also very simple, try reading some of the architecture tutorials here, they helped me a lot.
