The Seven Bridges of Königsberg
The Seven Bridges of Königsberg was a famous problem in mathematics and graph theory. The city, located in present-day Kaliningrad, Russia, had seven bridges connecting different parts of the city across the Pregel River. The challenge was to find a walk that would cross each bridge exactly once.
In 1736, the mathematician Leonhard Euler proved that such a walk was impossible. His work laid the foundation for the field of graph theory, which studies the properties of graphs and networks. The problem illustrated important concepts in mathematics, including the idea of vertices and edges.