Hey Madcow, you can make a building(s) like the ones made by Kravenwolf in his game Outbreak. Also you can make some walls that seem to be destroyed in the middle (like the Nazi Zombies game by Kravenwolf). Remember, to make the entities.
Also, they would look nice in a grungy texture.
Remember, FPSC uses 100 inches in length, breadth and height as the dimensions for a segment, so a wall should be 100 inches in the x or z axes and something like 4 inches in the y axes.
I can make buildings using SketchUp but the texturing is quite annoying using it, and I seem to be bad at creating textures (unless you expect me to take photographs, LOL!).
EDIT
I forgot to mention, you have some great textures in your warehouse entities.
And yeah, this post seems to view me as a Kravenfan, which I am.