Within a dense Polish woodland sits a forgotten complex with an explosive history. Also, grand coastal defences in Ghana reveal a tortured past, a decaying giant that had once promised to kick-start Serbia's industrial revolution, and a site built to keep America functioning in the aftermath of a nuclear war.

A two-hour special featuring a deserted Caribbean city, an American ghost town still burning, a Japanese no-go zone, an Arctic settlement facing a terrifying future, a sprawling Taiwanese facility that drew liquid gold down from the hills, and a once great lake that's now a barren desert.