Pentagon - Washington, D.C.
If you ever find yourself flying out of Ronald Reagan National Airport you should ask for a window seat on the left side of the plane (left side if you are facing the front of the plane). Soon after take off you will get an amazing view of the Pentagon. I managed to take this photograph but I couldn't quite frame it properly given the short time I had to get my camera out and position everything to avoid getting a photograph with a large section of the wing in it.
You can see the multiple "layers" of buildings in the photo. It's an excellent design as it allows many offices natural light. I often think every building should be built this way to give people more light and better views.