Lightroom has a neat tool for lens correction but you can also use to it fix more than that. I was at the Tom Bradley room (observation deck on the 27th floor of Los Angeles City Hall) and took this picture of the building across the street. The angle is downward as I am taking this shot from above.
Voila! After lens correction, it seems as if I’m taking this shot directly across from this building and the angles are all square. Cool!