The Incan ruins of Machu Picchu; protecting a fragile beauty in the modern world.

Conservationists turn killers in this battle to turn back time by eradicating mammal invaders threatening the islands' unique ecosystem.

Miners want to drill for billions of dollars worth of copper and gold beneath the wilderness of America's last wild frontier; fishermen say the world's last great salmon run could be jeopardized.

As sea levels rise, the sunken city of Heracleion sounds a warning of the growing threat faced by the planet's teeming coastal cities.

As deforestation rages and unique species vanish, the fight begins to save one of the planet's most special places before it is ruined forever.

In Patagonia, an American conservationist couple, Doug and Kristine Tompkins, purchased vast tracts of land to the fury of local developers. They wanted to protect as much South American biodiversity as they possibly could by creating a network of national parks on par with those in the United States.