But none of the TF2 textures are suitable for making simple brushwork skyscrapers, and I lack the artistic ability and technical prowess to make my own. I don't want to use HL2 textures because there are players who have TF2 and not HL2. A few textures with a window on an exterior wall would be very helpful, and appreciated.
One cheap trick I could use that might work is a 3D skybox with a thick fog, through which you could see the outline of some simple brushwork skyscrapers, but without being able to see the textures. I read that the 3D skybox has a separate fog, so I could have no fog at all inside the building, and a thick fog outside.
Another solution would be an overlay for a window that is frosted or dirty, so you can't see though it. the the outer wall of the building the players would be the outer edge of the map, and there would be no outside.
What we need is a place for talented artists to showcase their skies, as well as textures and models, and for mappers to browse for a sky (or texture o model) to use. Is there such a place? Before posting this request, I tried and failed to find one.