China's amazing Forbidden City.
"The largest palace complex built at any time in history."
An engineering wonder...
"How did they build?"
...made almost entirely of wood.
"It's a very sophisticated piece of woodworking."
And in one of the most earthquake-prone places in the world...
"Look at how solid it is."
...how has it survived for more than 600 years?
NOVA reveals the Secrets of the Forbidden City.