The Most Scary Roadway

I have seen this scary roadway through internet several times before and I had thought I myself would never have an opportunity to take this road but it happened to me during this trip to Zhang Jia Jie, China. It is literally thrilling to look down at the mountain roadway from the sky. I was wondering all the way up and down how this road was built. Anybody can give me an idea? :)

Heaven-linking Avenue has 99 turns symbolizing that the Heaven has nine palaces. The avenue runs upward with the posture of the mountain like the soaring of great dragon and also hangs like a jade belt with zigzag turns circling the hills. It is worth the title wonder of highway in the world. Through heaven-linking avenue, one reaches directly the Tianti-celestial ladder. The grand celestial like scene came into view.(quoted from a tourist guide book)

Tianmendong(天門洞) or Tianment Cave( Heaven Gate) is up there.