Tongtian Highway, Zhangjiajie, China (file photo)
Top 10: TongtianHighway, Zhangjiajie, China（中国张家界通天大道）
Tongtian Highway, located at the Tianmen Mountain National Forest Park in northwestern Hunan province, China, is a winding mountain road to the famous Tianmen Cave, which is located on the mountain peak. Measuring more than 10 kilometers (6.21 miles) in length and 200 meters (656.17 feet) to 1,200 meters (3,937 feet) 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 the "First wonder of China's highways."