Mathematics
The Seven Bridges of Königsberg Problem
Quick fact
Leonhard Euler's 1736 solution to the Königsberg bridge problem is widely considered the first theorem of graph theory, and his method of abstracting landmasses as points and bridges as lines laid the foundation for all modern network analysis.
Why this is interesting
Imagine trying to take a stroll through your city, crossing every bridge exactly once, without ever repeating one. In the old Prussian city of Königsberg, this simple puzzle stumped locals for years—until a mathematician turned it into the birth of an entire branch of science.