Tower over amazing metropolises. Learn why an important urban centre is sinking toward oblivion, soar over sprawling ruins buried under Saharan sands, learn the modern secret of an ancient fortress, and eye a ghost town on the edge of the Gobi.

Witness jaw-dropping animal spectacles from high above the Earth. Watch a whirling herd of northern nomads, see undersea behemoths show off in the Pacific shallows, track a US porcine stampede, and confront top ocean predators on the Florida coast.