We were asked to abstract a given image by drawing it only using parallel lines. (In this case it was Guggenheim Museum in Bilbao, Spain.) We were expected to give depth by using pencils of different hardnesses and the distance between our lines. I think the most important point was to be consistent in what we do.
I wanted to define my lines based on the locations of the elements in the photograph. I wanted to create the idea of depth and distance.