A couple of extra exercises exploring the difference between emphasising depth and suppressing it.
These are two images of the same building, taken with similar focal length and from a similar distance. The difference is that the top image is taken square-on and the lower image is taken at a corner, creating vanishing points and perspective lines, the same technique used by Atget in many of his images of the petits métiers of Old Paris (see Jeffrey, 2008: 30)
Of the two images above, the lower is cropped from the upper. This has the same effect as increasing the focal length and shooting from the same viewpoint.
Although the dominant (yellow) lines in both images are vertical and parallel to the frame edges, the upper image has some secondary perspective lines in the scaffold planks at the top of the image and some implied perspective lines joining the pads at the base of the poles. Cropping to exclude these perspective lines has removed most of the clues to the depth of the subject and flattened the pictorial frame.
Reference: Jeffrey, I (2008) How to Read a Photograph, London: Thames & Hudson