Take the Time to Really Get to Know the Space
To capture the essence of a building, whether inside or out, you’ll need to take some time to get to know it. On a practical level, this means scouting out the location, noticing how the sun travels, where the shadows are at different times of day, checking out the various access points, and seeing where lines converge.
Look for unusual angles and unusual perspectives. Notice if and when people are about and decide whether you want to include them in your shot.
On the conceptual side of things, do some research. Who built it? Why? Is there any compelling history? How have others photographed the building?
All of these things can significantly influence how you choose to go about capturing the space. Conversely, you can focus on just structure and geometry alone—just make sure to investigate all the possibilities.
Watch Your Lines
One of the most important keys to good architecture shots is to make sure your lines go precisely where they’re supposed to. Vertical lines should be vertical, horizontal lines, horizontal. Sounds elementary, but in reality, it can be very challenging, especially if you have to tilt the camera up to get all of a building in the frame.
Parallel lines will start to converge (also known as keystoning), and the building will look like it’s falling backwards. Also, if you’re using a wide-angle lens, you’ll probably have a fair amount of distortion to cope with.
For keystoning, try putting some distance between you and the building or getting to a higher point of view. A tilt-shift lens will also fix the problem, though it can be quite expensive.
For lens distortion (and for those of us who can’t afford a tilt-shift lens), you’ll need to fix things in post-processing.