Season 4 Episode 5
Beware the dangers that lie deep beneath South Africa, the source of the largest gold reserves in the world's deepest gold mine.
Below NYC, three subway projects are underway. Can they be built without disturbing the massive system already in place?
Turkey is making a clever move by harnessing the energy of the country′s powerful mountain waterfalls—a move that involves building a dizzyingly tall dam wedged between those very mountains.
To provide to water the metropolitan desert that is Los Angeles, two huge tunnels are being built along the (very active) San Andreas fault line.
In Kuala Lumpur, what protects from devastating floods also alleviates traffic congestion: the world′s first dual traffic/ water tunnel.