Cycles render showing up black and weird I'm trying to make an awesome render of an office building in Blender 2.7. Here's what it looks like in my 3D workspace view so far.


I've been toiling over the wire frame and 3D aspects of it, and then checking to see how it actually renders periodically. When I first started, it seemed to be rendering just fine. But then, when I was about 25% of the way done with building my model, I clicked render and this weird black image of it shows up. 

Also, I'm quite certain that it doesn't have to do with the lighting, as I have 4 lamps placed around the scene. I'm starting to get a little concerned that when I'm all done with pouring hours into this, I'm not going to be able to render it properly. Does anyone know what might be going wrong?

edit: I tried adding a white material to the floor part with the chairs on it, but it showed up like this: 



Here is the .blend:
The problem is that your entire building has a material on it "realistic glass"



Take this off and viola problem solved. If you would like to put glass on one part of the mesh see this question.