Geography
How Topographic Maps Represent Three-Dimensional Terrain
Quick fact
The first known topographic map was created in 1777 for military purposes in France, and the concept of contour lines was later fully developed by the British engineer John Henry Lefroy in the 19th century.
Why this is interesting
You look at a flat piece of paper and somehow see a mountain—how can a simple drawing capture the ups and downs of an entire landscape?