Tianmen Mountain in Zhangjiajie, China is known for its 99 sharp turns to reach the summit, 999 step staircase, and natural stone arch formed by the collapse of a cave 263 AD. Visitors can drive the winding road with scenic views, or take a cable car costing $38 for panoramic views, and must climb stairs to reach the base of the arch. Stunt pilots have famously flown planes through the large arch opening.