World War I ended 100 years ago on Sunday, but 42,000 acres in northeast France serve as a living memorial to the human and environmental costs of war.

The battle of Verdun was the longest continuous conflict in the Great War, and it so devastated the land it took place on that, after the war, the government cordoned it off-limits to human habitation. What was once farmland became the Zone Rouge, or Red Zone, as National Geographic reported.