After 4 sessions of Drawing 101 your lines take the directions you want. Straight, zigzagged or curved you’re ready to employ them to more than just decorative patterns.
Eiffel Tower‘s easy sketch is a mix of 4 long, vertical, slightly-curved lines cut by horizontal straight lines. Pay attention to the overall proportion: the tower base is one third of its height. The lowest two platforms don’t exceed one third of the entire height. Use long lines, don’t get stuck into detailing the base, then the first platform, and so on. Artists just break free their lines. Draw the tower 10 times and you’ll get an expressive sketch (more interesting than a precise drawing!).
Tip: If you want to add atmosphere (people or tree around), think big, think only at proportions. The tower is 300 meters (or 90 stories). People, trees and everything else fall under the big arch at the base.
Ziggurats have only straight lines, which make them easy steps forward in drawing. Ziggurats are actually terraced platforms. In the time of Ubaid pottery, in Mesopotamia (Trendy patterns in Ancient Near East ) people built massive mud-brick platforms (rectangular or oval-shaped) with flat tops. Their walls were sloped inward, like those of pyramid trunks.
Tip: Draw the frontal perspective: (1) Start with the biggest platform (a trapezoid). (2) Trace 2 slightly inclined vertical lines for stairs. (3) Add the smaller platform in front (an almost rectangular shape). (4) Add oblique lines on each side for lateral stairs. (5) Trace the platform (trapezoid) on the top. (6) Add details on the walls.
Both example are good to train your hand and eye for identifying surfaces and volumes. Don’t bother at this point with 3D views. Draw any building or object from its front. The beauty of your lines make the sketch as vivid as a 3D perspective.