Almost everyone knows what "the Pentagon" is. But did you know that, in the French media, the term l'Hexagone ("the Hexagon") is often used as a casual synonym for the mainland part of Metropolitan France? It is because of the country's approximate shape. The sides of the hexagon are: 1. the Channel coast, 2. the Atlantic coast, 3. the Pyrenees (border with Spain), 4. the Mediterranean coast, 5. the eastern border (Alps, Jura and Upper Rhine; Monaco to Karlsruhe), and 6. the northeastern border (German Rhineland and Belgium; Karlsruhe to Dunkirk).

More Info: en.wikipedia.org