Atlantic Wall
The Atlantic Wall was a series of fortifications along the Atlantic coast of Europe intended to prevent an Allied amphibious invasion during World War II. It consisted of minefields, tank obstacles, naval mines, artillery emplacements, concrete bunkers, barbed wire, and other obstacles. It was one of the most expensive building projects of the war.
In June 1944, the Allies landed in Normandy, avoiding the strongest part of the Wall in Calais. Within a few months, they broke out of Normandy, proving Hitler's investment in fixed defenses to have been an unwise strategy.
"Fixed fortifications are monuments to man’s stupidity.” - George S. Patton