In this tutorial, Moonboy shows some cool simple techniques to model based off images he found on the internet. A few loop cuts and extrusions add detail to the front facade of a building, and a simple cube with a texture provides a convincing glimpse into the interior. It's a great example of modeling 'only what you need' in a quick and relatively easy way.
I've mentioned this before, but I really enjoy these quick-paced and well edited tutorials that skip all the super obvious steps as well as errors made during the process.
