We had to take a picture of a building for our electronic imaging class and then fix the perspective in Photoshop. If you look really closely, you'll see that the three main verticals are vertical; however, I was using a wide angle lens, so the verticals in between are a little bowed due to lens distortion.
We also had to convert to BW using Photoshop's sweet BW conversion tool. Absolutely incredible. Helps that the sky was awesome.