Impressive ancient wisdom of Forbidden City water drainage

How does the water drainage work at the Forbidden City?

For more than six centuries, dragon-head water spouts have effectively drained excess rainwater. Despite the rain pouring down in Beijing on Saturday, visitors could still enjoy a spectacular view of the Forbidden City as this ancient but smart drainage design saved them from wading through water or getting stuck.

(Produced by Di Jingyuan, Cheng Ming and Dong Feng)