Keystoning is the term used to describe the "Leaning Tower of Pisa" effect of converging lines in architectural renderings. it's a very common result when rendering with a wide-angle lens. Photoshop can oftentimes straighten those buildings for you, correcting this perspective problem in a matter of seconds
Open your rendering in Photoshop, select the Crop tool from the toolbox, and drag the cursor from the top left corner to the bottom right corner and release. You will see the "marching ants" around your entire rendering. Go to the lower menu bar at the top of the screen and check the small box next to Perspective. Now, using the cursor, drag the top left corner of the marching ant border into the rendering so that the border is parallel to the tilting structure in the rendering. Do the same thing on the right side of the rendering. Then, double click in the rendering just to the right or left of the small center circle that appears on the rendering. Photoshop adjusts the image so that any tilting lines appear truly vertical, as they do when the human eye views the actual scene.