Tongtian Highway (Photo/Chinadaily.com.cn)

6. Tongtian Highway

Tongtian Highway, located at the Tianmen Mountain National Forest Park in central China's Hunan province, is a winding mountain road to the famous Tianmen Cave on the mountain peak. Measuring more than 10 kilometers in length and 200 meters to 1,200 meters above sea level, the road has 99 sharp turns. It took eight years and about 100 million yuan (US$16.2 million) to construct the road. The Tongtian Highway is known as China's "most spectacular road" for its 99 bends and beautiful scenery along the way.