If you dare to walk across the new see-through bridge in China's Siniuzhai Geopark, take comfort in the fact that the glass you are stepping on is 25 times stronger than window glass. You would certainly hope so, at 180m (590ft) off of the ground! The glass-bottomed bridge, in the Hunan province, recently replaced an old wooden one. Spanning 300m (984ft), the new bridge is the world's longest glass-bottomed walkway. It is already being dubbed 'hero bridge' in honor of those brave enough to walk across. Check it out!