Everyone's no doubt familiar with the Forbidden City in Beijing, but did you know that part of it was constructed with a little help of an "artificial ice path."

An article posted in the Proceedings of the National Academy of Sciences explains that this 70-kilometer frozen superhighway was created and maintained by 16th-century construction crews in order for them to slide those huge stones into Beijing. Researchers discovered this after combing through historic records, and were able to piece together just how this extraordinary freeway of ice was made.

First, a series of wells had to bee dug up every half-kilometer along the path from quarry to construction site. Water was then pumped up and spread across the ground before it was allowed to freeze. This resulted in the slippery road surface which was then used for easily transporting huge carved rocks.

There's a little debate as to the authenticity of those records, but you have to hand it to those ancient Chinese engineers for being able to think on their feet.

[Science News]