I was downtown yesterday for an event and took some architectural shots of the Wrigley Building and Tribune Tower. I took all of them with my Tokina 11-16mm - a great super wide angle lens that really captures straight lines well. The picture above, of Tribune tower, was edited in Photoshop. Here is a simple 5-step process to get this type of photo:

1. Open your original image in Photoshop

2. Duplicate the layer so you have two of the same image on top of one another

3. Make sure you select the top-most layer, and press ctrl (or command) + "u" to pull up the hue/saturation/contrast sliders

4. Drag the "saturation" slider all the way to the left - this will make that layer black and white

5. Now all you have to do is click on the eraser tool and erase the elements in the picture that you want in color!
Here are a couple more images from downtown: