Anyone with a fear of heights might want to avoid a new bridge in the European country of Portugal. The Ponte 516 Arouca bridge is a whopping 1,692 feet long, making it the longest suspension footbridge in the world. People who cross it get a good view of a roaring river 570 feet below. That’s because the bridge’s floor is a see-through metal grid. Even though the bridge is safely supported by sturdy steel cables, people still feel it wobble with every step.