Do you have LBS?

This is not good! Buildings have straight sides! Elevators do not travel upwards at an angle!
Here is a quick and dirty way the way to keep your building sides straight without dabbling in Photoshop adjustments:
1) use a wide angle lens, preferably a 12-20mm on an SLR (DX format), or an 18-24mm on an FX format camera.
2) Back up as far back as you need to go, preferably across, the street, keeping the camera PERFECTLY level with the ground, NOT leaning back, until you get the top of the building and the nice sky above it in the photo. (A tripod with a level is the best way to do this). Check to make sure the vertical edges of the building are PERFECTLY parallel to the vertical edges of your viewfinder.

3) Take the picture, and then, on the computer, crop out the street or grass at the bottom of the photo, giving you a square or rectangular format photo with a perfectly straight building.
We are happy to have David as one of our instructors at Penn Camera. He is teaching such popular Safaris as the Monuments at Night, Photography as a Second Career, the Fransiscan Monastery, and Regan National Airport Safari just to name a few. Check our website soon as we will be announcing some exciting new Safaris that you won't want to miss.
To find out more about the Washington Photo Safari, visit, www.WashingtonPhotoSafari.com