After the Escher project we started on a one point perspective.
The rules were to take a photo of a clearly defined one point perspective. Then either work from the photo or draw on site to recreate that one point perspective. Include any organic elements, but remove all people.
I was pretty successful with this project. It took me somewhere in the neighbor hood of 10-15 hrs. The only problem with it is that its not really dark enough, and I forgot to take pictures of my progress... oh well
Here is the original image
Here is the finished project (click to enlarge)