View whats not there?

Ok I have a question that I need some help with. So you know how on the evocity2 map how the tunnels bring you to a lower part of the map but you can still see through them and it gives you the effect that the maps continues in that direction. Well I have a Glass roof of a building on a map that peaks out of the grass. But there is not enough room for the building to fit under it b/c if tunnels and what not so I placed the tower above it, but I want the effect that it is still there underground. Is this possible?

http://img341.imageshack.us/img341/545/yeahhn.jpg

So like in this picture I still want the roof to be there but the actal rooms below it is actually above the place.

http://developer.valvesoftware.com/wiki/3d_skybox
:raise:

Why are there so many help threads on the main section! :suicide:

Because people can’t take the time to actually just post in The Question Megathread.

Ok sorry I am sort of new to face punch, so I will post in there now. Sorry for the inconvenience.

Have a heart.

Was the 3D skybox what you were looking for?

Yeah, I am looking at some tutorials online but still not sure how I can do this. How can I make it the real size so people see the room under that glass roof. Also will it not work if I already have another 3d skybox?

You can change the size of the scale by going to the sky_camera properties, there should be a scale keyvalue.

Ok cool, I will try that thanks.