Earlier this month, the officials of China's Hunan Province revealed what they believe will be a new "Wonder of the World" — the planet's longest and highest glass-bottom bridge. When complete, the 430 meter-long and 6 meter-wide structure will connect the two summits across the Zhangjiajie Grand Canyon. While the length is certainly impressive, it is the 400 m (1,312 ft) height that will have most visitors gripped by fear as they try to traverse across.